@article{MEM_2010_39_1_a28,
     author = {{\CYRB}{\cyre}{\cyrl}{\cyre}{\cyrv}, {\CYRD}{\cyri}{\cyrm}{\cyri}{\cyrt}{\cyrhrdsn}{\cyrr} and {\CYRI}{\cyrg}{\cyrn}{\cyra}{\cyrt}{\cyro}{\cyrv}{\cyra}-{\CYRB}{\cyre}{\cyrl}{\cyre}{\cyrv}{\cyra}, {\CYRV}{\cyra}{\cyrs}{\cyri}{\cyrl}{\cyrk}{\cyra}},
     title = {{\CYRE}{\cyrd}{\cyrn}{\cyro} {\cyro}{\cyrb}{\cyro}{\cyrb}{\cyrshch}{\cyre}{\cyrn}{\cyri}{\cyre} {\cyrn}{\cyra} {{\CYRN}{\cyra}{\cyrp}{\cyro}{\cyrl}{\cyre}{\cyro}{\cyrn}{\cyro}{\cyrv}{\cyri}{\cyrt}{\cyre}} {\cyrt}{\cyrr}{\cyri}{\cyrhrdsn}{\cyrg}{\cyrhrdsn}{\cyrl}{\cyrn}{\cyri}{\cyrc}{\cyri}},
     journal = {Mathematics and Education in Mathematics},
     pages = {257--261},
     publisher = {mathdoc},
     volume = {39},
     number = {1},
     year = {2010},
     language = {bg},
     url = {http://geodesic.mathdoc.fr/item/MEM_2010_39_1_a28/}
}