How do I fix bent paper back textbook covers?

Textbook buy back is coming up and some of my books were used to begin with, and the covers on the paper back books are curled out-wards a little.



Any ideas on how to make them more...presentable to get the most back that I can?How do I fix bent paper back textbook covers?
take a few thick rubber bands and place them evenly to the exact feeling you want it as--- then put something heavy on it and place it under the sink (like under the pipes) because its slightly damp (humid) allowing for it to loosen up to restructure. should work if you do it right