@article{MEM_2011_40_1_a10,
     author = {{\CYRS}{\cyrt}{\cyre}{\cyrf}{\cyra}{\cyrn}{\cyro}{\cyrv}, {\CYRK}{\cyrr}{\cyra}{\cyrs}{\cyre}{\cyrn} and {\CYRB}{\cyro}{\cyrishrt}{\cyrch}{\cyre}{\cyrv}, {\CYRP}{\cyra}{\cyrv}{\cyre}{\cyrl} and {\CYRS}{\cyrt}{\cyre}{\cyrf}{\cyra}{\cyrn}{\cyro}{\cyrv}{\cyra}, {\CYRE}{\cyrl}{\cyri}{\cyrz}{\cyra} and {\CYRG}{\cyre}{\cyro}{\cyrr}{\cyrg}{\cyri}{\cyre}{\cyrv}, {\CYRA}{\cyrt}{\cyra}{\cyrn}{\cyra}{\cyrs} and {\CYRN}{\cyri}{\cyrk}{\cyro}{\cyrl}{\cyro}{\cyrv}{\cyra}, {\CYRN}{\cyri}{\cyrk}{\cyro}{\cyrl}{\cyri}{\cyrn}{\cyra} and {\CYRG}{\cyrr}{\cyri}{\cyrg}{\cyro}{\cyrr}{\cyro}{\cyrv}, {\CYRA}{\cyrl}{\cyre}{\cyrk}{\cyrs}{\cyra}{\cyrn}{\cyrd}{\cyrhrdsn}{\cyrr}},
     title = {{\CYRC}{\cyri}{\cyrf}{\cyrr}{\cyro}{\cyrv}{\cyri}{\cyrt}{\cyre} {\cyrb}{\cyri}{\cyrb}{\cyrl}{\cyri}{\cyro}{\cyrt}{\cyre}{\cyrk}{\cyri} {\cyrv} {\cyro}{\cyrb}{\cyru}{\cyrch}{\cyre}{\cyrn}{\cyri}{\cyre}{\cyrt}{\cyro} {\cyrn}{\cyra} {\cyru}{\cyrch}{\cyri}{\cyrt}{\cyre}{\cyrl}{\cyri}},
     journal = {Mathematics and Education in Mathematics},
     pages = {120--135},
     publisher = {mathdoc},
     volume = {40},
     number = {1},
     year = {2011},
     language = {bg},
     url = {http://geodesic.mathdoc.fr/item/MEM_2011_40_1_a10/}
}