@article{MO_1999_a0,
     author = {I. V. Artamkin and A. L. Gorodentsev and A. G. Kulakov and {\CYRM}. {\CYRA}. {\CYRP}{\cyrr}{\cyro}{\cyrh}{\cyro}{\cyrr}{\cyro}{\cyrv} and S. M. Khoroshkin and {\CYRA}. {\CYRV}. {\CYRH}{\cyro}{\cyrh}{\cyrl}{\cyro}{\cyrv}},
     title = {Numbers and {Sums.} {Optional} {Course} in {Mathematics} for 13-15 years old students},
     journal = {Matemati\v{c}eskoe obrazovanie},
     pages = {2--57},
     publisher = {mathdoc},
     year = {1999},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MO_1999_a0/}
}