Laxmi Bachanalaya
Legally available public-domain books and openly licensed reading materials.
Jules Verne
Andre Norton
Harry Harrison
Owen Chase
E. E. Smith and Lee Hawkins Garby
E. E. Smith
John Jacob Astor
Philip K. Dick
Various
Poul Anderson
Charles L. Fontenay
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.