AHEAD Tutorial and Review Center uses the following sources as reference in developing its exam preparation materials:

GRE and TOEFL – ETS: https://www.ets.org/IELTS – https://www.ielts.org/

PhilSat – https://www.cem-inc.org.ph/philsat/
NMAT – https://www.cem-inc.org.ph/nmat/

SAT – https://www.collegeboard.org/
ACT – http://www.act.org/