The Monster Men

From Author Wars - https://authorwars.com/publications/the-monster-men-248470.html

Overview:

Title: The Monster Men
Author: Edgar Rice Burroughs
Year: 1972
Publisher: Ace Books
Price: $0.75
Pages: 155
Binding: Paperback
Type: Novel
Title Reference: The Monster Men
Notes:
• The only date is ©1913 for the base story A Man Without a Soul • Year derived from ads in the back, all of which appeared only in 1972 from May-August, month from Stuart Wells' Ace notebooks • The artist is not credited, no visible signature • Cover art credit from Enric's website