<p>Hello!</p>
<p>I just got invitation from my teacher to take the Chemistry Olympiad Regional Exam on March. I took AP Chem last year, and that is the only chemistry background. I borrowed Zumdahl Chemistry textbook (7th e/d) from my AP Chem teacher.</p>
<p>Now I have like two and half months to prepare for this exam (I heard that USAChO is even more difficult than USABO). I can recover the most materials since I read Zumdahl Chemistry (but that was last year). What kind of books should I buy? Is "Chemical Principles: A Quest for Insight" a textbook that can be read within two months? Do AP Chem prep books like Barrons or Princeton Review effective?</p>