| Author | Isaac Asimov |
| Copyright Holder | Nightfall, Inc. |
| Series | Robot |
| Publisher Series | Panther Science Fiction |
| Publisher | Panther, Panther Books, Granada Publishing Limited |
| First Published by | Victor Gollancz Ltd |
| Printed by | Richard Clay (The Chaucer Press) Ltd |
| Format | Paperback |
| Language | English |
| Location | UK |
| Copyright | 1976 |
| This Edition Published | 1978 |
| Pages / Font | 127 pages / Monotype times |
| ISBN | 0 586 04725 5 |
| Price | 85p U.K. |
| Price | $2.45 Australia |
| Price | $2.65 New Zealand |
Added by Supernaut1970