The Princess and the Thorn

From Author Wars - https://authorwars.com/publications/the-princess-and-the-thorn-284578.html

Overview:

Title: The Princess and the Thorn
Author: Paul R. Fisher
Year: 1980
ISBN-10: 0689307764
Publisher: Atheneum
Price: $8.95
Pages: 237
Binding: Hardcover
Type: Novel
Title Reference: The Princess and the Thorn
Notes: Stated First Edition Price and month of publication from Locus #237 (September 1980). Cover artist from: https://www.scribd.com/book/417558803/Book-Series-for-Children-1800-1990; Amazon.com's page also mentions David K. Stone as "Illustrator".