Extraterrestrial beings -- Juvenile fiction. Mice -- Juvenile fiction. Planets -- Exploration -- Juvenile fiction. Interplanetary voyages -- Fiction. Adventure and adventurers -- Fiction.

Ricotta, Ricky (Fictitious character) -- Juvenile fiction. Mice -- Juvenile fiction. Robots -- Juvenile fiction. Heroes -- Juvenile fiction. Monkeys -- Juvenile fiction.

Humorous stories. Mice -- Juvenile fiction. Superheroes -- Juvenile fiction. Stilton, Geronimo -- Juvenile fiction.

Robots -- Juvenile fiction. Middle schools -- Juvenile fiction. Schools -- Juvenile fiction. Family life -- Juvenile fiction. Inventors -- Juvenile fiction.

Gorilla -- Juvenile fiction. Robots -- Juvenile fiction. Contests -- Juvenile fiction. Humorous stories.