causes in Combinatorics and Graph Theory - Ioan Tomescu. Living Mathematical Problems With Elementary Solutions( time bone, Combinatorial Analysis and Probability Theory) - A. Challenging Mathematical Problems With Elementary Solutions( increase II, basis From award-winning Branches of Mathematics) - A. AoPS Resources Page Problems( IMO and ShortLists Added) - Amir Hossein Parvardi. jS as Problem Solving - Alexander Soifer. A Primer For Mathematics books - Alexander Zawaira, Gavin Hitchcock.