ebrary offers the most flexible options for acquiring eBooks and other authoritative content from the world's leading publishers. ebrary offers an increasing selection of more than 41,800 e-Books of 220 distinguished international publishers. 

Springer's Ebooks are available on perpetual access i.e. fully downloadable.

Digital Library has acquired McGraw Hill Collections for all the Digital Library registered institutions.

E books 

Ebooksgo provides you with free ebooks of engineering and technology such as electrical engineering, mechanical engineering, computer engineering, electronics engineering, civil engineering, architecture engineering, aircraft engineering, etc and more. All are free ebooks with free ebook licenses.

    O'REilly Books online More than 10,000 books are available.

Ebooksgo  provides you with free ebooks of engineering and technology such as Physics, electrical engineering, mechanical engineering, computer engineering, electronics engineering, civil engineering, architecture engineering, aircraft engineering, etc and more. All are free ebooks with free ebook licenses.

 Find Ebookee.com is a free search engine that  provides an option to search for and download various PDF&DOC documents, data sheets etc physics on engineering and technology.

Intech is an open-access site offering free reading and downloading of hundreds of books and a handful of journals in Physics. Especially well represented are Nanotechnology and Nanomaterials,Control Engineering & Robotics. 

Search and preview millions of books on Computer science from libraries and publishers worldwide using Google Book Search.