“…The following result is immediate. For future reference, we denote the four pairs of controllable graphs on six vertices by (CP 6,1 , CP 6,1 ), (CP 6,2 , CP 6,2 ), (CP 6,3 , CP 6,3 ) and (CP 6,4 , CP 6,4 ). These graphs can be identified from [2] as being the graphs with identification numbers (98, 46), (87, 67), (85, 60) and (77, 59) respectively.…”