@article{MEM_2010_39_1_a31,
     author = {{\CYRV}{\cyrhrdsn}{\cyrl}{\cyrk}{\cyra}{\cyrn}{\cyro}{\cyrv}{\cyra}, {\CYRV}{\cyre}{\cyrs}{\cyre}{\cyrl}{\cyri}{\cyrn}{\cyra} and {\CYRS}{\cyrt}{\cyro}{\cyrya}{\cyrn}{\cyro}{\cyrv}, {\CYRS}{\cyrt}{\cyra}{\cyrn}{\cyri}{\cyrm}{\cyri}{\cyrr} and {\CYRZ}{\cyre}{\cyrd}{\cyra}{\cyrn}, {\CYRH}{\cyryu}{\cyrs}{\cyre}{\cyri}{\cyrn} and {\CYRP}{\cyro}{\cyrp}{\cyrch}{\cyre}{\cyrv}, {\CYRI}{\cyrv}{\cyra}{\cyrn}},
     title = {{\CYRM}{\cyro}{\cyrd}{\cyre}{\cyrl} {\cyrz}{\cyra} {\cyri}{\cyrz}{\cyrs}{\cyrl}{\cyre}{\cyrd}{\cyrv}{\cyra}{\cyrn}{\cyre} {\cyrn}{\cyra} {\cyrk}{\cyrr}{\cyre}{\cyra}{\cyrt}{\cyri}{\cyrv}{\cyrn}{\cyro}{\cyrt}{\cyro} {\cyrm}{\cyri}{\cyrs}{\cyrl}{\cyre}{\cyrn}{\cyre} {\cyri} {\cyrd}{\cyre}{\cyrishrt}{\cyrs}{\cyrt}{\cyrv}{\cyri}{\cyre} {\cyrn}{\cyra} {\cyru}{\cyrch}{\cyre}{\cyrn}{\cyri}{\cyrc}{\cyri}},
     journal = {Mathematics and Education in Mathematics},
     pages = {274--280},
     publisher = {mathdoc},
     volume = {39},
     number = {1},
     year = {2010},
     language = {bg},
     url = {http://geodesic.mathdoc.fr/item/MEM_2010_39_1_a31/}
}