These receipts look like your grocery store receipts and some people have taken to using them as their bookmarker. Others have left them in the little pockets of the book jacket.
I love when people leave them in the book jacket pockets. It gives me a little peek into what some people are checking out of the library. And sometimes you can get some good reading suggestions from these receipts.
The other day I found a receipt in the back of the book I just picked up from the library. I ordered The King Of Lies by John Hart. In the back was a receipt from the last person and they got this book and The House at Riverton by Kate Morton. Hmmmmm....never heard of that one but I'm going to check it out!