For Your Information: The Hollow Earth
| First published | March 1956 |
|---|---|
| Type | Essay |
| Series | For Your Information |
Publications (2)
| Date | Publication | Publisher | Type | Page |
|---|---|---|---|---|
| March 1956 | Galaxy Science Fiction, March 1956 | Galaxy Publishing Corporation | MAGAZINE | 71 |
| May 1956 | Galaxy Science Fiction, No. 38 | Strato Publications | MAGAZINE | 69 |