Those Who Watch

From Author Wars - https://authorwars.com/publications/those-who-watch-422050.html

Overview:

Title: Those Who Watch
Author: Robert Silverberg
Year: 1967
Publisher: Signet / New American Library of Canada
Price: C$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
- Cover printed in the US, book in Canada