12 books
The Flaming Mountain A Rick Brant Science-Adventure Story
The Caves of Fear
The Wailing Octopus
The Pirates of Shan
The Flaming Mountain
The Scarlet Lake Mystery
The Flying Stingaree
Rip Foster in Ride the Gray Planet - Scholar's Choice Edition
The Blue Ghost Mystery
The Egyptian Cat Mystery
The Caves of Fear by John Blaine, Science Fiction, Fantasy
Rip Foster in Ride the Gray Planet