Google Scholar

In a user-centric knowledge-pull model for learning management, we need intelligent search engines to locate e.g. quality learning resouces. Google Scholar is a good example of a search engine that is capable of ranking the search results based on relevance. Anurag Acharya, principal engineer at Google writes "Google Scholar is a free service that helps users search scholarly literature such as peer-reviewed papers, theses, books, preprints, abstracts and technical reports. Just as with Google Web Search, Google Scholar orders your search results by how relevant they are to your query, so the most useful references should appear at the top of the page. This relevance ranking takes into account the full text of each article as well as the article's author, the publication in which the article appeared and how often it has been cited in scholarly literature. Google Scholar also automatically analyzes and extracts citations and presents them as separate results, even if the documents they refer to aren't online. This means your search results may include citations of older works and seminal articles that appear only in books or other offline publications".