Mathematical Puzzles for Math Enthusiasts

Math Circle by the Bay: Topics for Grades 1-5 (MSRI Mathematical Circles Library)

Math from Three to Seven: The Story of a Mathematical Circle for Preschoolers (Msri Mathematical Circles Library)

A Moscow Math Circle: Week-by-week Problem Sets (Msri Mathematical Circles Library)

A Decade of the Berkeley Math Circle: The American Experience: 2 (Msri Mathematical Circles Library): The American Experience, Volume II