The Biodiversity Heritage Library (BHL) is a consortium of natural history and botanical libraries worldwide that cooperate to digitize and make accessible the legacy literature of biodiversity held in their collections and to make that literature available for open access and responsible use as a part of a global biodiversity commons. BHL also serves as the foundational literature component of the Encyclopedia of Life (EOL) with access provided to texts with information on over 150 million species names.
A repository of scanned books contributed from academic institutions across the United States, including UC campuses, and those digitized by Google and the Internet Archive. Books still in copyright are scanned and searchable, but the full text scans will not become available online until their copyright expires. Although there is significant overlap with Google books, this site has a much more effective and sophisticated search interface. For additional details, see the HathiTrust Help Page.
Allows searching of the full text "of more than 7,500 of Charles Darwin’s letters" and locating "information on 7,500 more. [Includes] complete transcripts of all known letters Darwin wrote and received up to the year 1869."