CORE (COnnecting REpositories) provides a comprehensive bibliographic database of the world’s scholarly literature including theses, collecting and indexing research from repositories and journals.
BASE is one of the world's most voluminous search engines especially for academic web resources. The index contains more than 400 million records from more than 11,000 content providers. You can access the full texts of about 60% of the indexed records for free (Open Access). BASE is operated by Bielefeld University Library