@article{MEM_2011_40_1_a5,
     author = {{\CYRD}{\cyri}{\cyrm}{\cyrk}{\cyro}{\cyrv}, {\CYRG}{\cyre}{\cyro}{\cyrr}{\cyrg}{\cyri}},
     title = {{\CYRM}{\cyra}{\cyrt}{\cyre}{\cyrm}{\cyra}{\cyrt}{\cyri}{\cyrk}{\cyra} {\cyri} {\cyrm}{\cyru}{\cyrz}{\cyri}{\cyrk}{\cyra} ({\cyro}{\cyrt} {{\CYRP}{\cyri}{\cyrt}{\cyra}{\cyrg}{\cyro}{\cyrr}} {\cyrd}{\cyro} {{\CYRB}{\cyra}{\cyrh}} {\cyri} {\cyrd}{\cyro} {\cyrn}{\cyra}{\cyrsh}{\cyri} {\cyrd}{\cyrn}{\cyri})},
     journal = {Mathematics and Education in Mathematics},
     pages = {80--88},
     publisher = {mathdoc},
     volume = {40},
     number = {1},
     year = {2011},
     language = {bg},
     url = {http://geodesic.mathdoc.fr/item/MEM_2011_40_1_a5/}
}