If you only download five files, make it these:

By Titu Andreescu and Bogdan Enescu. Though technically international, these books are the standard textbooks for Singapore’s training camps.

In this context, Singapore Math Olympiad books are viewed as a shortcut to cognitive excellence. They are perceived as a rigorous training regimen that can "hack" a student’s intellectual potential. The search for the PDF is a frantic attempt to bypass the logistics of shipping and cost to immediately begin the mental conditioning required to compete on a global stage. It reflects a world where the race for academic supremacy has no borders, and where Singapore is viewed as the ultimate training ground.