Scopus

The Scopus database contains records from 1969 including science, mathematics, engineering, technology, health and medicine, social sciences, arts and humanities.

• 22,800 peer reviewed journals, including 3,800 open access titles.
• 280 trade publications.
• Articles in press [accepted for publication] from more than 8,000 publishers.
• 150,000 books from Science, Technology & Medicine (2005-present ) and Arts & Humanities (2003-present).
• 8 million conference papers from 100,000 conferences.
• 39 million patents.

Web of Science (WoS)

The WoS database contains records from 1900 including sciences, social sciences, arts and humanities.

• 20,300 peer reviewed journals.
• 94,000 scholarly books (2005-present).
• 10 million conference papers.
• coverage in some fields is less complete than in others, and there is an apparent focus in the sciences.

Google Scholar

Google Scholar is a freely accessible 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 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.