Might be a weird place to start, but I found Selwyn Raab's 'Five Families' incredibly dry at first. Picked it up thinking it was all hits and wiretaps, but it's basically a textbook. Stuck with it because I was researching for a story, and the detail on how the Commission actually functioned, the business meetings about territory and tribute... it stripped away the Hollywood glamour completely. That’s the history for me. It explains why these structures endured, not just the bloody moments that get turned into movies.
For a boots-on-the-ground counterpoint, Joseph Pistone's 'Donnie Brasco' is essential. The history isn't in dates, it's in the mundane, grating reality of being a wiseguy. The constant scamming for pocket money, the petty humiliations within the hierarchy. It shows the system from the inside, rotting from tedium and mistrust as much as from RICO. The movie’s fantastic, but the book has this weary, claustrophobic texture the film can only hint at.