| Author | Isaac Asimov |
| Series | Robot |
| Publisher | Edhasa |
| Publisher Series | Colección Nebulae |
| Series Director | Miguel Masriera |
| Translated by | Manuel Bosch Barrett |
| Printed by | Imprenta Moderna |
| Format | Soft cover |
| Language | Spanish |
| Location | Barcelona, Spain |
| This Edition Published | 1956 |
| Pages / Font | 261 pages |
| Volume Number | 17 |
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