Sivashinsky IH, Boltyanskii V. (eds.) Problems in Mathematics for extracurricular activities (9 - 10 grades). - M., Education, 1968. - 314 p.

 The book is intended for teachers, leading the work of circle; it can be used, and high school students interested in mathematics. Material benefits distributed to 32 sessions. Each lesson contains tasks from different branches of mathematics. In the second part of the book shows the solution to the problems and instructions.