| Author | Robert A. Heinlein, Anson MacDonald |
| Copyright Holder | Robert A. Heinlein |
| Series | Panther Science Fiction |
| Publisher | Panther Books, Granada Publishing Limited |
| First Published by | Sidgwick & Jackson Limited |
| Printed by | Cox & Wyman Ltd |
| Format | Paperback |
| Language | English |
| Location | UK |
| Copyright | 1948 |
| Reprinted | 1974 |
| Pages / Font | 204 pages |
| Other | 586 02348 8 |
| Price | 35p |