I. V. Artamkin, A. L. Gorodentsev, A. G. Kulakov, М. А. Прохоров, S. M. Khoroshkin, А. В. Хохлов, “Numbers and Sums. Optional Course in Mathematics for 13-15 years old students”, Math. Ed., 1999, Issue 2-3(9-10),Pages <nobr>2

Textbook in the journal

Numbers and Sums. Optional Course in Mathematics for 13-15 years old students

I. V. Artamkin, A. L. Gorodentsev, A. G. Kulakov, М. А. Прохоров, S. M. Khoroshkin, А. В. Хохлов