Chicago Mobs of the Twenties

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Chicago Mobs of the Twenties was a reference book, written by Billings and Torgelson (TOS novel: Starfleet: Year One) and released by book publishers Simon and Schuster in November 1992 (TOS novel: The Rise and Fall of Khan Noonien Singh, Volume 2) The book was a history of the mob in the Earth city of Chicago during the 1920's.

ECS Horizon crewman Nora kept a hardcopy on a shelf in her quarters, when friend Travis Mayweather spoke to her, in private. (ENT episode: "Horizon")

When the Horizon visited Sigma Iotia II in 2156, the book was left behind by the ship's crew, along with other materials by the crew of the Horizon. The Iotians viewed the society depicted in the book as ideal, and rebuilt their own accordingly. (TOS episode: "A Piece of the Action"; ENT novel: Kobayashi Maru)

Earlier sources have suggested the USS Horizon (NCC-176) was the vessel that left the book.

Simon and Schuster, coincidentally, is the parent company of Pocket Books, the licensee for Trek fiction from 1979 onward.