Use for old textbooks

Whenever my husband needs a weight for something, the first thing he reaches for is my old nursing school textbooks. When he needs to go on a ruck march, a few of these quickly add up to the 30-50 lbs he needs to weigh down his backpack. Unable to use a vise clamp for glue work, such as the time when he wanted to apply pressure to our t-molding strips over the newly installed kitchen floor, a couple of hand bells and my nursing text books were called up for duty. So if you're about to graduate from nursing school, unless you want to retain those books as really expensive weights, sell them back. On second thought, do they even print up these monstrosities anymore? Perhaps there's now an apps instead of textbooks.