1961. The Edge of Tomorrow. 120 pp, 17.5 cm, 1st. Jun'61 pbk, (reprinted in Time and the Riddle, 1975). Bantam (A2254). New York.*
| 1961. | 120 pp, 17.5 cm, pbk, Bantam Books of Canada (A2254). Montreal. | |
| 1962. | 125 pp, pbk, Transworld Pub. (Corgi Books). London. | |
| 1966. | 120 pp, 17.5 cm, pbk, Bantam (F3309) (3rd). New York.* |