The Zero Stone

From Author Wars - https://authorwars.com/publications/the-zero-stone-141831.html

Overview:

Title: The Zero Stone
Author: Andre Norton
Year: 1968
Publisher: The Viking Press
Price: $4.50
Pages: 286
Binding: Hardcover
Type: Novel
Title Reference: The Zero Stone
Notes:
"First published in 1968" on the copyright page. [Currey] A catalogue number or other identification was not stated. Month of publication from The Whole Science Fiction Data Base 7. Artist from the Andre Norton Books website