<p>Many faculty stay with old edition as long as possible so they don’t have to upgrade their courses (page references, homework problems, etc.). The problem is that the publisher stops printing the old edition and faculty are then forced to roll to the new edition. I remember one summer when I wasn’t ready to go to new edition yet and our bookstore had to get creative to find enough books from the old edition to provide inventory for the course. Bookstore manager really wanted me to upgrade, but I insisted that I was not ready to upgrade the course in the 2-3 weeks that I would have had. He had to scramble.</p>