A lot of books are on sale at the Bangor Public Library – donated books, to help raise money.The Friends of the Library support group is hosting its annual book sale. Friday is preview night for Friends’ members. It runs from 5 p.m. to 6:30 p.m and if you’re not a member, you can join at the door and get in. There’s a 20-book limit. Saturday, the sale opens to the public from 9 a.m to 1 p.m.Paperbacks are 50 cents to $1. Hardbacks are $2. At least 10,000 books are up for grabs.