<p>I’m self-studying a few of those right now. If you are familiar with the subject, it’s usually only necessary to buy a good prep book (1Princeton Review , 2Barron’s, 3Cliff Notes, etc.) online. I usually order through Amazon. If it is a topic completely new to you, then buying a textbook is a good idea also. Look into what textbook nearby schools use for that subject, and purchase online, either through a mass company like Amazon (which I recommend if you can find what you need) or from a textbook speciality, like abebooks. </p>
<p>Good Luck! :)</p>