- Listenly
- Public Library
- Project Gutenberg
- Space flight — Juvenile fiction
Space flight — Juvenile fiction — Audiobooks
Rip Foster Rides the Gray Planet
by Harold L. (Harold Leland) Goodwin
Rip Foster in Ride the Gray Planet
by Harold L. (Harold Leland) Goodwin
The Planet Mappers
by E. Everett (Edward Everett) Evans
Young Visitor to Mars
by Richard M. (Richard Mace) Elam