"The National Academies—National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council—are committed to distributing their reports to as wide an audience as possible. Since 1994 we have offered “Read for Free” options for almost all our titles. In addition, we have been offering free downloads of most of our titles to everyone and of all titles to readers in the developing world."
http://notes.nap.edu/2011/06/02/more-than-4000-national-academies-press-pdfs-now-available-to-download-for-free/
