For Your Information: The Hollow Earth
From Author Wars - https://authorwars.com/books/for-your-information-the-hollow-earth-116396.html
Overview:
Editions/Publications:
- Unknown. Galaxy Science Fiction, March 1956 (Unknown, Willy Ley, Galaxy Publishing Corporation, $0.35, 148 pages, digest, MAGAZINE)
- Unknown. Galaxy Science Fiction [UK], No. 38 (Unknown, Willy Ley, Strato Publications, 2/-, 132 pages, digest, MAGAZINE)