Triangle

From Author Wars - https://authorwars.com/publications/triangle-52326.html

Overview:

Title: Triangle
Author: Sondra Marshak, Myrna Culbreath
Year: Unknown
ISBN-10: 0671743511
Publisher: Pocket Books
Price: $4.95
Pages: 188
Binding: Paperback
Type: Novel
Title Reference: Triangle
Notes:
Ninth Printing Image is of the tenth printing amazon has a date of 1988-03 associated with the ISBN but the 8th printing was in 1989 [no surprise they're wrong as usual]