The X Factor

From Author Wars - https://authorwars.com/publications/the-x-factor-259482.html

Overview:

Title: The X Factor
Author: Andre Norton
Year: 1974
Publisher: Ace Books
Price: $1.25
Pages: 158
Binding: Paperback
Type: Novel
Title Reference: The X Factor
Notes:
- No printing or edition stated.
- Date from OCLC
- The copyright page credits Jack Gaughan for the cover and interior art but it's very unlikely he did this cover.
- This and #92551 are the only two Ace 5-digit publications of this title prior to 1975, according to a bibliography by Helen-Jo Jakusz Hewitt published in 1975 publication "The Book of Andre Norton"
- 441 92553 125 on Spine; results in ISBN 0441925537