Couple of Outfit books:

organized crime in chicago, beyond the mafia by lombardo. Kind of a socialogical explanation for OC in Chicago. Includes an interesting section of the original street crew neighberhoods of the outfit: Taylor street, Grand ave and so on.

The mafia court, corruption in Chicago by Hughes. More of an ordinary chronical of the usual faces, had hoped for more of a detailed story of the inner workings of the corruption.