The calculus book my university used was a loose-leaf "custom edition" which came in shrink wrap. My cal IV prof told the class first day: "I cannot advise you to go down to the copy shop and run off copies of the relevant chapters for your friends. That would be theft and is illegal. Again, I cannot recommend that you go down to the copy shop next to Pizza Hut on Jackson Avenue and run off copies of the relevant chapters for your friends. That is illegal."