From: Star Trek: The Original Series
Caption: The Iotian "bosses" confer
Planet: Sigma Iotia II
Highly intelligent and imitative humanoid species who model their social practices after a single Federation book that was left in the Iotian's possession before Starfleet's Prime Directive came to be. The resulting societal changes reflected the book from which they had come, "Chicago Mobs of the Twenties."