From the site: “The Biodiversity Heritage Library (BHL) is a consortium of natural history and botanical libraries 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 content may be freely viewed through the online reader or downloaded in part or as a complete work in PDF, OCR text, or JPG2000 file formats. ” Browsing is available by Title, Author, Subject, and Year. Searching can be done by Author, Subject, Scientific Name, and Book/Journal Title. The record or the full book can be viewed. More than 53,000 titles and 102,000 volumes can be browsed or searched, including over 1 million species. Rare scientific texts are also shown.