By Vincent Bugliosi with Curt Gentry. Funny thing about Helter Skelter -- I never seem to get used copies I can sell. Dog-eared all to hell, covers coming off...people really read it hard, this book. Even a newer edition like this one finds a creative way to be messed up.
It's not unreadable, mind you -- some edgewear, but clean pages, sits pretty straight. It's just that bowing of the pages of the front half of the book, which actually you could probably "train out of" them by storing it between a couple dictionaries for a week. It's not a fatal flaw, though, and for the price, you can probably live with it.