Those Who Watch

From Author Wars - https://authorwars.com/publications/those-who-watch-51173.html

Overview:

Title: Those Who Watch
Author: Robert Silverberg
Year: 1967
Publisher: Signet / New American Library
Price: $0.60
Pages: 143
Binding: Paperback
Type: Novel
Title Reference: Those Who Watch
Notes:
- "First Printing, April, 1967"; no number line
- The artist is not credited, no visible signature
- Printed in the US