|BASE (Bielefeld Academic Search Engine)
||BASE is one of the world's most voluminous search engines especially for academic open access web resources and is operated by Bielefeld University Library. BASE collects, normalizes, and indexes data from repository servers that use use the "Open Archives Initiative Protocol for Metadata Harvesting" (OAI-PMH) for providing their contents. BASE provides more than 36 million documents from more than 2,200 sources. You can access full text for about 75% of the indexed documents.