<p>All of my kids used older editions. Just e-mail professors and put it past them.When you get the book just be sure to match up the chapters with your course guide because they may be out of sequence. Math books may also be missing some problems but again the savings may be worth getting copies from the library and making the adjustments. They also purchased foreign editions although science books are not recommended due to lack of color print in the diagrams. Many foreign texts will have a lower quality paper but the savings are often worth the difference.</p>