Google Scholar is a freely available web search engine that indexes the full text or metadata of scholarly literature across an array of publishing formats and disciplines. Released in beta in November 2004, the Google Scholar index includes most peer-reviewed online academic journals and books, conference papers, theses and dissertations, preprints, abstracts, technical reports, and other scholarly literature, including court opinions and patents. While Google does not publish the size of Google Scholar’s database, third-party researchers estimated it to contain roughly 160 million documents as of May 2014.
Google Scholar – Search Tips – Get the most out of Google Scholar with some helpful tips on searches, email alerts, citation export, and more.
Google Scholar Metrics – Google Scholar Metrics provide an easy way for authors to quickly gauge the visibility and influence of recent articles in scholarly publications.