Travel books - how long to keep?
Over the last 20-25 years, I've been fortunate to have traveled around the world. For each trip, I've purchased guide books to the place I've gone. As a result, now I'm looking at books like 1985 guides to Italy, 1989 guides to Germany and 1992 guides to Egypt (and lots more). But I'm also looking at fairly cluttered bookshelves which need cleaning out.
How long would you keep travel materials and do you think there is a garage sale type market for the older things?