This page provides a full timeline of web search engines, starting from the

WHOis WHOIS (pronounced as the phrase "who is") is a query and response protocol that is used for querying databases that store an Internet resource's registered users or assignees. These resources include domain names, IP address blocks and autonomo ...

in 1982, the Archie search engine in 1990, and subsequent developments in the field. It is complementary to the history of web search engines page that provides more qualitative detail on the history.

Timeline

Feinler set up a server in Stanford's Network Information Center (NIC) which acted as a directory that could retrieve relevant information about people or entities. She and the team created domains, with Feinler's suggestion that domains be divided into categories based on the physical address of the computer. , - , 1990 , , September , , 10 (released) , , Pre-web content search engine , , The Archie search engine, created by Alan Emtage computer science student at

McGill University McGill University (French: Université McGill) is an English-language public research university in Montreal, Quebec, Canada. Founded in 1821 by royal charter,Frost, Stanley Brice. ''McGill University, Vol. I. For the Advancement of Learning, ...

Montreal Montreal is the List of towns in Quebec, largest city in the Provinces and territories of Canada, province of Quebec, the List of the largest municipalities in Canada by population, second-largest in Canada, and the List of North American cit ...

, goes live. The program downloads the directory listings of all the files located on public anonymous FTP (

File Transfer Protocol The File Transfer Protocol (FTP) is a standard communication protocol used for the transfer of computer files from a server to a client on a computer network. FTP is built on a client–server model architecture using separate control and d ...

) sites, creates a searchable database of a lot of file names; however, Archie does not index the contents of these sites since the amount of data is so limited it can be readily searched manually. , - , 1991 , , , , , , Pre-web search engine , , The rise of

Gopher Pocket gophers, commonly referred to simply as gophers, are burrowing rodents of the family Geomyidae. The roughly 41 speciesSearch results for "Geomyidae" on thASM Mammal Diversity Database are all endemic to North and Central America. They ar ...

(created in 1991 by Mark McCahill at the

University of Minnesota The University of Minnesota Twin Cities (historically known as University of Minnesota) is a public university, public Land-grant university, land-grant research university in the Minneapolis–Saint Paul, Twin Cities of Minneapolis and Saint ...

) leads to two new search programs, Veronica and Jughead. Like Archie, they search the file names and titles stored in Gopher index systems. Veronica (''V''ery ''E''asy ''R''odent-''O''riented ''N''et-wide ''I''ndex to ''C''omputerized ''A''rchives) provides a keyword search of most Gopher menu titles in the entire Gopher listings. Jughead (''J''onzy's ''U''niversal ''G''opher ''H''ierarchy ''E''xcavation ''A''nd ''D''isplay) is a tool for obtaining menu information from specific Gopher servers. While the name of the search engine "Archie" was not a reference to the Archie comic book series, " Veronica" and " Jughead" are characters in the series, thus referencing their predecessor. , - , 1992 , , , , , , Virtual library of the web , ,

Tim Berners-Lee Sir Timothy John Berners-Lee (born 8 June 1955), also known as TimBL, is an English computer scientist best known as the inventor of the World Wide Web, the HTML markup language, the URL system, and HTTP. He is a professorial research fellow a ...

sets up the Virtual Library (VLib), a loose confederation of topical experts maintaining relevant topical link lists. , - , rowspan="4" , 1993 , June , , , , First web robot , , Matthew K. Gray produces the first known web robot, the

Perl Perl is a high-level, general-purpose, interpreted, dynamic programming language. Though Perl is not officially an acronym, there are various backronyms in use, including "Practical Extraction and Reporting Language". Perl was developed ...

-based World Wide Web Wanderer, and uses it to generate an index of the web called the Wandex. However, the World Wide Web Wanderer is intended only to measure the size of the web rather than to facilitate search. , - , September , , 2 , , First web search engine , ,

W3Catalog W3 Catalog was an early web search engine, first released on September 2, 1993 by developer Oscar Nierstrasz at the University of Geneva. The engine was initially given the name ''jughead'', but then later renamed. Unlike later search engines, lik ...

, written by Oscar Nierstrasz at the

University of Geneva The University of Geneva (French: ''Université de Genève'') is a public university, public research university located in Geneva, Switzerland. It was founded in 1559 by French theologian John Calvin as a Theology, theological seminary. It rema ...

, is released to the world. It is the world's first web search engine. It does not rely on a crawler and indexer but rather on already existing high-quality lists of websites. One of its main drawbacks is that the bot accesses each page hundreds of times each day, causing performance degradation. , - , October/November , , , , Second web search engine , ,

Aliweb ALIWEB (Archie-Like Indexing for the Web) is the first Web search engine. First announced in November 1993 by developer Martijn Koster while working at Nexor, and presented in May 1994 at the First International Conference on the World Wide W ...

, a web search engine created by

Martijn Koster Martijn Koster (born ca 1970) is a Dutch software engineer noted for his pioneering work on Internet searching. Koster created ALIWEB, the Internet's first search engine, which was announced in November 1993

, is announced. It does not use a web robot, but instead depends on being notified by website administrators of the existence at each site of an index file in a particular format. The absence of a bot means that less bandwidth is used; however, most website administrators are not aware of the need to submit their data. , - , December , , , , First web search engine to use a crawler and indexer , ,

JumpStation JumpStation was the first WWW search engine that behaved, and appeared to the user, the way current web search engines do. It started indexing on 12 December 1993 and was announced on the Mosaic "What's New" webpage on 21 December 1993. It was h ...

, created by Jonathon Fletcher, is released. It is the first WWW resource-discovery tool to combine the three essential features of a web search engine (crawling, indexing, and searching). , - , rowspan="5" , 1994 , rowspan="2", January , , , New web directory , ,

Yahoo! Yahoo (, styled yahoo''!'' in its logo) is an American web portal that provides the search engine Yahoo Search and related services including My Yahoo, Yahoo Mail, Yahoo News, Yahoo Finance, Yahoo Sports, y!entertainment, yahoo!life, and its a ...

, founded by Jerry Yang and David Filo, launches Yahoo! Directory. It becomes the first popular

Web directory A web directory or link directory is an online list or catalog of websites. That is, it is a directory on the World Wide Web of (all or part of) the World Wide Web. Historically, directories typically listed entries on people or businesses, and the ...

. , - , , , New web search engine , ,

Infoseek Infoseek (also known as the "big yellow") was an American internet search engine founded in 1994 by Steve Kirsch. Infoseek was originally operated by the Infoseek Corporation, headquartered in Sunnyvale, California. Infoseek was bought by The W ...

is launched. , - , March , , , , New web search engine , , The

World-Wide Web Worm The World Wide Web Worm (WWWW) was one of the earliest search engines for the World Wide Web (WWW). It was developed in September 1993 by Oliver McBryan at the University of Colorado as a research project. It is claimed by some to be the first sea ...

is released. It is claimed to have been created in September 1993, at which time there did not exist any crawler-based search engine, but it is not the earliest at the time of its actual release. It supports

-based regular expressions. , - , April , , 20 , , New web search engine , , The

WebCrawler WebCrawler is a search engine, and one of the oldest surviving search engines on the web today. For many years, it operated as a metasearch engine. WebCrawler was the first web search engine to provide full text search. History Brian Pinker ...

search engine, created by Brian Pinkerton at the

University of Washington The University of Washington (UW and informally U-Dub or U Dub) is a public research university in Seattle, Washington, United States. Founded in 1861, the University of Washington is one of the oldest universities on the West Coast of the Uni ...

, is released. Unlike its predecessors, it allows users to search for any word in any webpage, which has become the standard for all major search engines since. , - , July , , , , New web search engine , ,

Lycos Lycos, Inc. (stylized as LYCOS), is a web search engine and web portal established in 1994, spun out of Carnegie Mellon University. Lycos also encompasses a network of email, web hosting, social networking, and entertainment websites. The company ...

, a web search engine, is released. It began as a research project by

Michael Loren Mauldin Michael Loren "Fuzzy" Mauldin () (born March 23, 1959) is an American retired computer scientist and the inventor of the Lycos web search engine. He has written 2 books, 10 refereed papers, and several technical reports on natural-language p ...

of Carnegie Mellon University's main

Pittsburgh Pittsburgh ( ) is a city in Allegheny County, Pennsylvania, United States, and its county seat. It is the List of municipalities in Pennsylvania#Municipalities, second-most populous city in Pennsylvania (after Philadelphia) and the List of Un ...

campus. , - , rowspan="4", 1995 , , , , , New search engine , ,

Yahoo! Search Yahoo! Search is a search engine owned and operated by Yahoo!, using Microsoft Bing to power results. Originally, "Yahoo! Search" referred to a Yahoo!-provided interface that sent Web search query, queries to a searchable index of pages supple ...

is launched. It is a search function that allows users to search Yahoo! Directory. It becomes the first popular search engine on the Web. However, it is not a true

Web crawler Web crawler, sometimes called a spider or spiderbot and often shortened to crawler, is an Internet bot that systematically browses the World Wide Web and that is typically operated by search engines for the purpose of Web indexing (''web spider ...

search engine. , - , , , , , New search engine , , Search.ch is launched. It is a

search engine A search engine is a software system that provides hyperlinks to web pages, and other relevant information on World Wide Web, the Web in response to a user's web query, query. The user enters a query in a web browser or a mobile app, and the sea ...

and

web portal A web portal is a specially designed website that brings information from diverse sources, like emails, online forums and search engines, together in a uniform way. Usually, each information source gets its dedicated area on the page for displayin ...

for

Switzerland Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...

. , - , , , , , New web directory , ,

LookSmart LookSmart is an American search advertising, content management, online media, and technology company. It provides search, machine learning and chatbot technologies as well as pay-per-click and contextual advertising services. LookSmart a ...

is released. It competes with

as a web directory, and the competition makes both directories more inclusive. , - , December , , , , Web search engine supporting natural language queries , ,

Altavista AltaVista was a web search engine established in 1995. It became one of the most-used early search engines, but lost ground to Google and was purchased by Yahoo! in 2003, which retained the brand, but based all AltaVista searches on its own sear ...

is launched. This is a first among web search engines in many ways: it has unlimited bandwidth, allows natural language queries, has search tips, and allows people to add or delete their domains in 24 hours. , - , rowspan="4", 1996 , , , , , New web search engine , ,

Robin Li Robin Li Yanhong (; born 17 November 1968) is a Chinese software engineer and billionaire internet entrepreneur who is the co-founder and chief executive officer of Chinese multinational technology company Baidu. As of May 2025, his net worth wa ...

developed the

RankDex Baidu, Inc. ( ; ) is a Chinese multinational technology company specializing in Internet services and artificial intelligence. It holds a dominant position in China's search engine market (via Baidu Search), and provides a wide variety of o ...

site-scoring algorithm for search engines results page ranking and received a US patent for the technology. It was the first search engine that used hyperlinks to measure the quality of websites it was indexing, predating the very similar algorithm patent filed by

Google Google LLC (, ) is an American multinational corporation and technology company focusing on online advertising, search engine technology, cloud computing, computer software, quantum computing, e-commerce, consumer electronics, and artificial ...

two years later in 1998.

Larry Page Lawrence Edward Page (born March 26, 1973) is an American businessman, computer engineer and computer scientist best known for co-founding Google with Sergey Brin. Page was chief executive officer of Google from 1997 until August 2001 when ...

referenced Li's work as a citation in some of his U.S. patents for

PageRank PageRank (PR) is an algorithm used by Google Search to rank web pages in their search engine results. It is named after both the term "web page" and co-founder Larry Page. PageRank is a way of measuring the importance of website pages. Accordin ...

. Li later used his Rankdex technology for the

Baidu Baidu, Inc. ( ; ) is a Chinese multinational technology company specializing in Internet services and artificial intelligence. It holds a dominant position in China's search engine market (via Baidu Search), and provides a wide variety of o ...

search engine. , - , January–March, , , , New web search engine , ,

and

Sergey Brin Sergey Mikhailovich Brin (; born August 21, 1973) is an American computer scientist and businessman who co-founded Google with Larry Page. He was the president of Google's parent company, Alphabet Inc., until stepping down from the role on D ...

begin working on BackRub, the predecessor to

Google Search Google Search (also known simply as Google or Google.com) is a search engine operated by Google. It allows users to search for information on the World Wide Web, Web by entering keywords or phrases. Google Search uses algorithms to analyze an ...

. The crawler begins activity in March. , - , May , , , , New web search engine , ,

Inktomi Inktomi Corporation was an American Internet service provider (ISP) software developer based in Foster City, California. Customers included Microsoft, HotBot, Amazon.com, eBay, and Walmart. The company developed Traffic Server, a proxy se ...

releases its HotBot search engine. , - , October, , , , New web search engine , , Gary Culliss and Steven Yang begin work at MIT on the popularity engine, a version of the Direct Hit Technologies search engine that ranks results across users according to the selections made during previous searches. , - , rowspan="3", 1997 , April , , , , New natural language-based web search engine , ,

Ask Jeeves Ask.com (known originally as Ask Jeeves) is an answer engine, e-magazine, and former web search engine, operated by Ask Media Group. It was conceptualized and developed in 1996 by Garrett Gruener and David Warthen (based in Berkeley, Califo ...

, a natural language web search engine, that aims to rank links by popularity, is released. It would later become Ask.com. , - , rowspan="2", September , 15 , , New web search engine , , The domain Google.com is registered. Soon, Google Search is available to the public from this domain (around 1998). , - , 23 , , New web search engine (non-English) , , Arkady Volozh and Ilya Segalovich launch their Russian web search engine

Yandex Yandex LLC ( rus, Яндекс, r=Yandeks, p=ˈjandəks) is a Russian technology company that provides Internet-related products and services including a web browser, search engine, cloud computing, web mapping, online food ordering, streaming ...

and publicly present it at the Softool exhibition in Moscow. The initial development is by Comptek; Yandex would become a separate company in 2000.About Yandex — History of Yandex
Retrieved May 24, 2011
Archived copy
, - , rowspan="3", 1998 , June, , 5 , , New web directory , , Gnuhoo, a web directory project by Rich Skrenta and Bob Truel, both employees of

Sun Microsystems Sun Microsystems, Inc., often known as Sun for short, was an American technology company that existed from 1982 to 2010 which developed and sold computers, computer components, software, and information technology services. Sun contributed sig ...

, launches. It would later be renamed the Open Directory Project. , - , July–September , , , , New web search portal , , MSN launches a search portal called MSN Search, using search results from

. After many changes to the backend search engine, MSN would start developing in-house search technology in 2005, and later change its name to

Bing Bing most often refers to: * Bing Crosby (1903–1977), American singer * Microsoft Bing, a web search engine Bing may also refer to: Food and drink * Bing (bread), a Chinese flatbread * Bing (soft drink), a UK brand * Bing cherry, a varie ...

in June 2009. , - , August, , , , New web search engine , , Direct Hit Technologies releases their popularity search engine in partnership with HotBot, providing more relevant results based on prior user search activity. , - , 1999 , , May , , , , New web search engine , , AlltheWeb, based on the Ph.D. thesis of Tor Egge at the

Norwegian University of Science and Technology The Norwegian University of Science and Technology (NTNU; ) is a public university, public research university in Norway and the largest in terms of enrollment. The university's headquarters is located in Trondheim (city), Trondheim, with region ...

, titled ''FTP Search'', launches. The engine is launched by Egge's company

Fast Search & Transfer Microsoft Development Center Norway (known as FAST (Fast Search & Transfer ASA) before 2010) is a Norway, Norwegian company, founded in 1997 and based in Oslo, with offices located in Germany, Italy, Sri Lanka, France, Japan, the United Kingdom, ...

, established on July 16, 1997. , - , 2000 , , January , , 1 , , New web search portal , ,

, a Chinese company that would grow to provide many search-related services, launches. It was founded by

, who previously developed

in 1996. , - , 2002–03 , , , , , , Web search business consolidation , ,

buys Inktomi (2002) and then Overture Services Inc. (2003) which has already bought AlltheWeb and

. Starting 2003, Yahoo! starts using its own Yahoo Slurp web crawler to power

. Yahoo! Search combines the technologies of all Yahoo!'s acquisitions (until 2002, Yahoo! had been using Google to power its search). , - , 2004–05 , , November (2004) – February (2005) , , , , Change in backend providers , , Microsoft starts using its own indexer and crawler for MSN Search rather than using blended results from

and

. , - , 2004 , , December , , , , User experience , , Google Suggest is introduced as a Google Labs feature. , - , rowspan="2", 2005 , January , , , , Webmaster tools , , To combat link spam,

and

Microsoft Microsoft Corporation is an American multinational corporation and technology company, technology conglomerate headquartered in Redmond, Washington. Founded in 1975, the company became influential in the History of personal computers#The ear ...

collectively introduce the

nofollow nofollow is a setting on a web page hyperlink that directs search engines not to use the link for page ranking calculations. It is specified in the page as a type of link relation; that is: <a rel="nofollow" ...>. Because search engi ...

attribute. , - , October , , , , New web search engine , , Overture Services Inc. owner Bill Gross launches the Snap search engine, with many features such as display of search volumes and other information, as well as sophisticated auto-completion and related terms display. It is unable to get traction and soon goes out of business. , - , 2006, , December , , 23 (proposed) , , rowspan="2" , New human-curated web search engine , , Wikia Search (

Wikia Fandom (formerly known as Wikicities and Wikia) is a wiki hosting service that hosts wikis mainly on entertainment topics (i.e., video games, TV series, movies, entertainers, etc.). The Privately held company, privately held for-profit Delaware ...

), a search engine based on human curation. , - , 2007 , January, , 31 (re-proposed), , ''Wikia Search'' , - , rowspan="2", 2008 , January , , 28 , , New web search engine , , Cuil, a web search engine created by ex-Googlers that uses picture thumbnails to display search results, launches.Liedtke, Michael,
Ex-Google engineers debut 'Cuil' way to search
', Associated Press, 28 July 2008, retrieved 13 Dec 2009 It would later shut down on September 17, 2010. , - , September , , 25, , New web search engine, , DuckDuckGo (DDG), a web search engine focused on protecting searchers'

privacy Privacy (, ) is the ability of an individual or group to seclude themselves or information about themselves, and thereby express themselves selectively. The domain of privacy partially overlaps with security, which can include the concepts of a ...

by not profiling its users, launches. , - , rowspan="5" , 2009 , March–May, , 14, , Web search EOL, , shutdown of ''Wikia Search'' Wales giving up on Wikia Search
/ref> , - , July , , 29 , , Web search engine consolidation , ,

and

announce that they have made a ten-year deal in which the Yahoo! search engine would be replaced by Bing. Yahoo! will get to keep 88% of the revenue from all search ad sales on its site for the first five years of the deal, and have the right to sell adverts on some Microsoft sites. Yahoo! Search will still maintain its own

user interface In the industrial design field of human–computer interaction, a user interface (UI) is the space where interactions between humans and machines occur. The goal of this interaction is to allow effective operation and control of the machine fro ...

, but will eventually feature "Powered by Bing™" branding. , - , August , , 10 (announced) , , Search algorithm update , , Named ''

Caffeine Caffeine is a central nervous system (CNS) stimulant of the methylxanthine chemical classification, class and is the most commonly consumed Psychoactive drug, psychoactive substance globally. It is mainly used for its eugeroic (wakefulness pr ...

'', it promises faster crawling, expansion of the index, and a near-real-time integration of indexing and ranking. , - , September , , 1 , , New web search engine , , The search engine

ImHalal I'mHalal.com was a search engine built on top of social-cultural Islamic values. The search engines algorithm differed from regular search engines because the relevancy of the results was based on the culture, mindset and lifestyle of Muslims. Th ...

is launched built on top of social-cultural Islamic values. , - , December , 7 , New web search engine , The search engine

Ecosia Ecosia (derived from "Ecology, eco" and "utopia") is a non-profit tech organisation based in Berlin, Germany. It runs its namesake internet search engine, which launched on 7 December 2009 to coincide with 2009 United Nations Climate Change Con ...

is launched. , - , rowspan="3", 2010 , June, , 8 , , Search algorithm update, , ''Caffeine'' rollout completed and made live , - , September , , 8 , , User experience , , Google launches Google Instant, described as a ''search-before-you-type'' feature: as users are typing, Google predicts the user's whole search query (using the same technology as in Google Suggest, later called the autocomplete feature) ''and'' instantaneously shows results for the top prediction. Google claims that this is estimated to save 2–5 seconds per search query. SEO commentators initially believe that this will have a major effect on

search engine optimization Search engine optimization (SEO) is the process of improving the quality and quantity of Web traffic, website traffic to a website or a web page from web search engine, search engines. SEO targets unpaid search traffic (usually referred to as ...

, but soon revise downward their estimate of the impact. , - , November , , 1 , , New web search engine , , Blekko, a search engine that uses slashtags to allow people to search in more targeted categories, launches. , - , rowspan="2", 2011 , February , , 23–24 , , Search algorithm update , , Google launches

Google Panda Google Panda is an algorithm used by the Google search engine, first introduced in February 2011. The main goal of this algorithm is to improve the quality of search results by lowering the rankings of websites with "low-quality content". Panda is ...

, a major update affecting 12% of search queries. The update continues with the earlier work of cracking down on spam, content farms, scrapers, and websites with a high ad-to-content ratio. The rollout is gradual over several months, and Panda will see many further updates. , - , June , , 2 , , Webmaster tools , ,

, and

announce Schema.org, a joint initiative that supports a richer range of tags that websites can use to convey better information. , - , rowspan="4", 2012 , January , , 10 , , Search algorithm update, user experience , , Google launches Search Plus Your World, a deep integration of one's social data into search. SEO commentators are critical of how the search results favor

Google+ Google+ (sometimes written as Google Plus, stylized as G+ or g+) was a Social networking service, social network owned and operated by Google until it ceased operations in 2019. The network was launched on June 28, 2011, in an attempt to challe ...

and push it to users, compared to more widely used social networks such as

Facebook Facebook is a social media and social networking service owned by the American technology conglomerate Meta Platforms, Meta. Created in 2004 by Mark Zuckerberg with four other Harvard College students and roommates, Eduardo Saverin, Andre ...

and

Twitter Twitter, officially known as X since 2023, is an American microblogging and social networking service. It is one of the world's largest social media platforms and one of the most-visited websites. Users can share short text messages, image ...

. , - , April , , 24 , , Search algorithm update , , Google launches its "Webspam update" which would soon become known as

Google Penguin Google Penguin is a codename for a Google algorithm update that was first announced on April 24, 2012. The update was aimed at decreasing search engine rankings of websites that violate Google's Webmaster Guidelines by using now declared Grey Hat ...

. , - , rowspan="2", May , 10 , , User experience , , Microsoft announces a redesign of its

search engine that includes "Sidebar", a social feature that searches users' social networks for information relevant to the search query. , - , 16 , , Search algorithm update , , Google starts rolling out

Knowledge Graph In knowledge representation and reasoning, a knowledge graph is a knowledge base that uses a Graph (discrete mathematics), graph-structured data model or topology to represent and operate on data. Knowledge graphs are often used to store interl ...

, used by Google internally to store semantic relationships between objects. Google now begins displaying supplemental information about objects related to search queries on the side. , - , rowspan="3", 2013 , April , 13 , New web search engine , Pipilika, first Bangla search engine, launched. , - , July , , 4 , , New web search engine , , French search engine

Qwant Qwant () is a French search engine launched in February 2013. Qwant says that it is focused on privacy, does not track users, reselling personal data, or bias the display of search results. Its results are similar to Microsoft's Bing search en ...

launched and operated from Paris. It claims that it does not employ user tracking or personalize search results in order to avoid trapping users in a filter bubble. The search engine is available in 26 languages. , - , September , , 26, , Search algorithm update , , Google releases Google Hummingbird, a core algorithm update that may enable a more semantic search and more effective use of the

in the future. , - , rowspan="2", 2014 , January , 22 , New web search engine , Searx, a free and open-source metasearch engine, is launched. Searx puts an emphasis on privacy. , - , July , 24 , Search algorithm update , Google introduces Google Pigeon, with the goal of increasing the ranking of local listings in a search. , - , 2021 , June , 21 , New web search engine , Brave Software, Inc., the developer of the Brave web browser, launches their own search engine, called Brave Search. , , - , 2024 , July , 26 , New web search engine ,

OpenAI OpenAI, Inc. is an American artificial intelligence (AI) organization founded in December 2015 and headquartered in San Francisco, California. It aims to develop "safe and beneficial" artificial general intelligence (AGI), which it defines ...

launches SearchGPT, a prototype search engine that combines traditional search engine features with generative AI capabilities. SearchGPT's architecture is built on the principles of transformer models, which use self- attention mechanisms to process and generate text.

References

{{Timelines of computing Web search engines Web search engines

Timeline

See also

References