Each book in the library had a card in a pocket attached to inside cover. And each user had a number of pocket tickets with their name and address on. When you borrowed the book they took the card and put it in one of your pocket tickets and put that in a rack in date order. The number of mini folders with your name determined how many books you could borrow,Library catalogues consisting of large wooden cabinets with multiple drawers containing filed cards with details of each book in the stock typed separately on each card.
And of course they stamped the due date on a sheet inside the book
Today I use my bus pass to borrow books