Business or Blood page p220

" Gallo didn't seem nervous about trying to come back to Montreal. Did he think Vito hadn't detected the depth of his betrayal ? He was too smart and experienced a man to truly believe that. De he feel he might somehow be forgiven for transferring Vito's sports book to the Toronto area to the Calabrians during his absence ? Other sport books operations had been turned over to Montagna. In Vito's world betrayed accounts were closed with bullets. Gallo knew all this, and yet he agreed to the meeting in the Dominican."

So now we know there are several books.