These are well-researched books available for download. More books will be added soon. I do not own all of these materials. I just found it useful and would like to help other for them to have a material for learning.

Mathcounts Handbook .

Schaum’s Easy Outlines in Abstract Algebra

Calculus, Early Transcendentals 6th ed

Number Theory Problems for IMO

Probability and Statistics for Engineering and Sciences

Probability and Combinations Practice Problems For Beginners

Philippine Mathematical Olympiad Problem Compilations

Philippine Statistics Quiz (PSQ) Reviewer

MTAP Reviewers for 4th Year By Russelle Guadalupe

Answer Keys to 5 sets of Reviewer