The Secret of the Ninth Planet

From Author Wars - https://authorwars.com/publications/the-secret-of-the-ninth-planet-204085.html

Overview:

Title: The Secret of the Ninth Planet
Author: Donald A. Wollheim
Year: 1965
Publisher: Paperback Library
Price: $0.50
Pages: 155
Binding: Paperback
Type: Novel
Title Reference: The Secret of the Ninth Planet
Notes:
• "First Printing: November, 1965"; no number line • Cover artist is uncredited and signature is not visible on the artwork • LCCN is on copyright page.