American Mathematical Society Circles: (Russian Experience)

Mathematical Circles: Russian Experience (Mathematical World, Vol. 7)

A Moscow Math Circle: Week-by-Week Problem Sets (MSRI Mathematical Circles Library) (MSRI Mathematical Circles Library, 8)

A Decade of the Berkeley Math Circle: The American Experience (MSRI Mathematical Circles Library) (v. 1) (MSRI Mathematical Circles Library, 1)