More than once, New York Mob member "Lefty" (Al Pacino), brags to Johnny Depp (playing an undercover FBI agent) all he has done (hits) for the Mob:
"So when they open the books, they will find my name".
Who specifically in the MOB is "they"? Are these physical books? Are they metaphorical books? The Book of Mormon?
Having an actual book with Mob members written down would seem problematic given the line of work they are in. But Al Pacino mentions it several times, and he seems very proud of it.