Electronic Books - Digital Collections, many are subscription databases.

The proliferation of personal electronic reading devices today - Kindle -Nook - iPad, and so on, means that there is a burgeoning market for electronic full text of books and other materials. In addition, libraries are also buying current electronic texts and making them available to their clientel. With these markets for e texts, many current books can be purchased in electronic form, and copyright matters are happily dealt with by original contract with the writers / editors.

However, for older books, originally issued in paper format long before electronic form was envisioned, there is a wasteland stretching from 1923 until the present, excepting those recent titles where electronic editions have been contracted for. There is an ugly specter of copyright enfringement, the ill tempered dragon lurking in the Elysean Fields where electronic text might - perhaps - otherwise join traditional paper format to enrich scholarship in older materials. Those materials still under copyright - in the United States, those from 1923 to the present, but published before electronic editions were thought of and so included in publishing contracts. For example, the Tasini Case in the Supreme Court ( New York Times Co. v. Tasini - 533 U.S. 483 (2001) ) decided that electronic publishing is new publishing, and must be covered in an explicit agreement with the copyright holder of the material.

Through the Main Catalog of the Princeton University Library, direct access is provided to many thousands of full text books and other full text titles. Of the full text projects, two are of special note for their scale and the weight of materials they contain, Project Gutenberg and HathiTrust.

Project Gutenberg. Open Internet, <http://www.gutenberg.com>
Begun in 1971, Project Butenberg is oldest full text project, which is populated by volunteers converting books in the public domain to electronic format. It is as platform independent as possible, on the open Internet. In 2012, contatins some 40,000 titles.

Hathitrust. Open Internet searching, <http://www.hathitrust.org>
Begun in 2008. Access to available full text by subscription, which Princeton has. In 2012, holds some 10 million titles, 2.7 million have full text available,. Content is based on Google Books, on Internet Archives, and on titles digitized by member libraries, such as Princeton.

One powerful feature of Hathitrust is that it allows searching through the full text of all ten million titles, even if only a snippit of text containing the searched term can be shown, along with the page number and citation for the work. A paper copy of the material thus identified can then be consulted. This same searching is available in Goodle Books, which is a subset of the Hathitrust content. <http://books.,google.com>

A Sampler of Additional Electronic Text Projects available at Princeton includes the following.
( For those not on the Open Internet, go to the ARTICLES AND DATABASES link on the library home page, and search by title.)

EBRARY - Contains some 20,000 titles
Gale Virtual Reference Library
Past Masters - Search by individual author / title
Knovel Engineering and Scientific Online References
Safari Tech Books Online

However, it is important to note that digital text is a field whose growth is explosive and changes rapidly. Perhaps in the future the question of fair recompense of copyright holders in the recent past can be resolved, and much more electronic content of that material can be made available. .