Basically the title. Also, when did you start studying for this test/when do you recommend to start studying for this test? Thanks.
I would recommend either Princeton review or Barrons. Those are the two generic test prep companies and usually do a good job covering all the necessary material.
As for studying, I would tell you to start as soon as possible. Be advised, the chemistry subject test is not an easy exam. In the world of subject tests, I would place it at the more difficult end of the spectrum.