The Door Into Summer

From Author Wars - https://authorwars.com/publications/the-door-into-summer-411163.html

Overview:

Title: The Door Into Summer
Author: Robert A. Heinlein
Year: 1964
Publisher: Signet / New American Library of Canada
Price: C$0.50
Pages: 159
Binding: Paperback
Type: Novel
Title Reference: The Door Into Summer
Notes:
- "First Printing, March, 1964"; no number line
- Statement refers to first Canadian printing, first US printing was in 1959
- Artwork is the same as the first printing [reduced] which was signed by Lehr
- Cover printed in the US, book in Canada