Laxmi Bachanalaya
Legally available public-domain books and openly licensed reading materials.
Frederic E. Clements
Alexander von Humboldt
A. F. W. Schimper
Alfred Russel Wallace
Wilhelm Bölsche
Arabella B. Buckley
These books are free to read. Each is in the public domain in the United States; check your own country's rules before you copy or share one.