This trilogy is set in the chronology of Isaac Asimov 's " Robot " series , between the novels " The Robots of Dawn " and " Robots and Empire " .
Head entity: the robots of dawn Q440784 20 21 22 23
Tail entity: robots and empire Q377230 27 28 29
Relation (head \u2192 tail): P156
Inverse relation (tail \u2192 head): P155