How to Boost Chem and History SAT 2's

<p>Hey everyone, I took APUSH and AP Chem last year and at the end of the year, I took the subject tests but only received a 720 and 730, respectively. As I am hoping for Ivy’s if at all possible, is there any way i can boost those by October? What books should I use to study and what should i Study? thanks in advance</p>

<p>anyone have insight or suggestions?</p>