While discussing abandoned books with a friend today, my example was the Close Encounters of the Third Kind tie-in novelization.
I started digging in in late 1979, and in November of that year I packed it in. The real part of this story is the fact that for almost thirty-nine years the bookmark was exactly where I left it: Chapter 10.
The book was unremarkable, like most of that kind, and added nothing to what to me was an unremarkable movie -- sans a few show pieces.
The bookmark: "Half Back - The Ontario Rebate Program that turns old Wintario tickets into discounts", valid from May 1 - September 30, 1979.