Fortress in Time

From Author Wars - https://authorwars.com/books/fortress-in-time-904137.html

Overview:

Title: Fortress in Time
Author: Kurt Mahr
Year: 1978
Type: Short Fiction

Editions/Publications:

Unknown. Perry Rhodan #123: Fortress in Time (Unknown, Kurt Mahr, Master Publications, $1.95, 68 pages, digest, MAGAZINE)