Currently college textbook publishers often require students to obtain a special access code, which often costs as much as a new textbook and is only usable once, and which is not usable by purchasers of second-hand textbooks. This forces many students to buy new textbooks despite the existence of many lower-cost second-hand books.
We propose that these access codes be required to be transferable between subsequent users of a textbook. This would allow students to sell their used textbooks along with the necessary access codes to other students.