Bielefeld Academic Search Engine
Operated by the Bielefeld University Library, BASE offers over 100 million documents from over 4,000 sources with 60% full text that can be selected.
Google Scholar
Indexes peer-reviewed papers, theses, books, abstracts and articles from academic publishers, professional societies, preprint repositories, universities and other scholarly organizations.
Microsoft Academic
Pulls content from over 120 million publications, including scientific papers, conferences and journals.
Refseek
This search engine pulls from over one billion web pages, encyclopedias, journals, and books. It is similar to Google in its functionality, except that it focuses more on scientific and academic results—meaning more results will come from .edu or .org sites, as well as online encyclopedias. It also has an option to search documents directly—providing easy access to PDFs of academic papers.
