The Door Into Summer

From Author Wars - https://authorwars.com/publications/the-door-into-summer-416839.html

Overview:

Title: The Door Into Summer
Author: Robert A. Heinlein
Year: 1966
Publisher: Signet / New American Library of Canada
Price: C$0.60
Pages: 159
Binding: Paperback
Type: Novel
Title Reference: The Door Into Summer
Notes:
• "Second Printing, May, 1966"; no number line • Statement refers to CDN printings only, there were three US printings to this date • The artist is not credited, the uncropped artwork shows Lehr's signature • Printed in Canada