The Mirror

From Author Wars - https://authorwars.com/publications/the-mirror-274297.html

Overview:

Title: The Mirror
Author: Marlys Millhiser
Year: 1980
ISBN-10: 0449241874
Publisher: Fawcett Crest
Price: $2.50
Pages: 352
Binding: Paperback
Type: Novel
Title Reference: The Mirror
Notes:
"First Fawcett Crest printing: January 1980"
Number line "10 9 8 7 6 5 4 3 2 1"
No credit given for cover art.