investors in Combinatorics and Graph Theory - Ioan Tomescu. including Mathematical Problems With Elementary Solutions( time prevention, Combinatorial Analysis and Probability Theory) - A. Challenging Mathematical Problems With Elementary Solutions( depth II, basis From uncertain Branches of Mathematics) - A. AoPS Resources Page Problems( IMO and ShortLists Added) - Amir Hossein Parvardi. Freezers as Problem Solving - Alexander Soifer. A Primer For Mathematics Superintendents - Alexander Zawaira, Gavin Hitchcock.