%0 Journal Article %A V. I. Voytitsky %T Gifts from Santa Claus or variations on the themes of the classics %J Matematičeskoe obrazovanie %D 2021 %P 28-37 %V 100 %N 4 %I mathdoc %U http://geodesic.mathdoc.fr/item/MO_2021_100_4_a5/ %G ru %F MO_2021_100_4_a5