9 books • 2 series
The Monster That Threatened the Universe
The Red Planet (The Classical Library)
Message from Venus
Equation for Time
The Thought-Men of Mercury - Asteroid of the Damned (Great Science Fiction Short Stories, #3)
The Whispering Spheres
Comet
Gene Autry, Cowboy Detective
Red Ryder and the Mystery of the Whispering Walls