All these books are free to read: either they're distributed with a free license, or they're in the public domain.
keyword: Science – 128 free books.
These books are included in the Directory of Open Access Books. This means that they have been peer-reviewed and are of interest to scholars.
Michael Dawson et al.
Gordana Dodig-Crnkovic and Marcin J. Schroeder
F.G. (Frank) Bosman
Bretislav Friedrich et al.
Ungyu Paik and Jea-Gun Park