I'd recommend "The Art and Craft of Problem Solving" by Paul Zeitz, who coached the U.S. International Mathematical Olympiad team. https://www.amazon.com/exec/o

I'd recommend "The Art and Craft of Problem Solving" by Paul Zeitz, who coached the U.S. International Mathematical Olympiad team. https://www.amazon.com/exec/obidos/ASIN/0471789011/artofproblems-20 https://www.amazon.com/exec/obidos/ASIN/0471789011/artofprob...