Ebrary features a growing selection of more than 36,000 titles from more than 200 leading academic, scientific, technical, medical, and professional publishers.
The Directory of Open Access Books is a discovery service for peer reviewed books published under an Open Access license. DOAB provides a searchable index to the information about these books, with links to the full texts of the publications at the publisher’s website or repository.
The Universal Digital Library, a book-scanning project backed by several major libraries across the globe, has completed the digitization of 1.5 million books and made them free and publically available. Make sure to download a free TIFF or DjVu plugin.
Books in Print
Information and reviews for in-print, out-of-print, and forthcoming books, audio books, and videos. Includes access to Non-Fiction Connection, Fiction Connection and Global Books in Print.
Gale Encyclopedia of Science by 
McGraw-Hill Concise Encyclopedia of Science and Technology by 
Encyclopedia of Scientific Principles, Laws, and Theories by 