Base: Bielefeld Academic Search Engine
BASE is one of the world's most voluminous search engines especially for academic web resources. BASE is operated by Bielefeld University Library.
BASE collects and indexes the metadata of web documents, provides more than 90 million documents from more than 4,000 sources. You can access the full texts of about 60% of the indexed documents for free (Open Access).
The CORE collection contains millions of Open Access publications aggregated from institutional repositories, archives and journals. The collection is mainly composed of research articles from both humanities and sciences.
RefSeek is a web search engine for students and researchers that aims to make academic information easily accessible to everyone. RefSeek searches more than one billion documents, including web pages, books, encyclopedias, journals, and newspapers.
WorldWideScience is a global science gateway comprised of national and international scientific databases and portals.
Mit Google Scholar können Sie eine allgemeine Suche nach wissenschaftlicher Literatur durchführen.
System for Information on Grey Literature in Europe. OpenGrey is your open access to 700.000 bibliographical references of grey literature (paper) produced in Europe and allows you to export records and locate the documents.
Microsoft Academic is a free public web search engine for academic publications and literature.
ScienceResearch.com is a one-stop, deep web search portal designed for science researchers everywhere. It helps provide researchers with quick access to information from a multitude of credible collections.
Semantic Scholar finds peer-reviewed research from the world's most trusted sources (PubMed, Nature, ArXiv, etc.)