So, I did not receive transfer credit for my DE course. The instructor sent out an email that we would be dropped from the course, if we did not have the current edition of Boyce Di Prima DE. I would not mind purchasing an older edition from amazon, but to spend $100 on a textbook that I will not have no use for after, NO!!!! Since I already took this class. I went through both a copy of Zill (the mandatory class text) and Ross: DE. I studied from Ross and used Zill as a problem book. I looked at Boyce and it is inferior in all aspects to Ross. Can the teacher actually drop me from his class for not having the newest edition of a book?