I'ma assume, like the above, you mean fiction books, and not non-fiction....
Not wholly about time travel, per se, but it is a plot device, and a very good read anyway :
Greg Bear's The Way
The Way of All Ghosts.
Edit : Do yourself a favour, and stay well away from anything by Michael Crichton.
Edit 2 : Just been through my library and a couple of titles spring out : Millennium
by John Varley.
Also made into a film that wasn't half-bad. By His Bootstraps
by Robert Heinlein.