Voir la notice de l'article provenant de la source Math-Net.Ru
@article{MP_1961_a22, author = {V. A. Efremovich}, title = {{\CYRN}{\cyra}{\cyrg}{\cyrl}{\cyrya}{\cyrd}{\cyrn}{\cyrery}{\cyrishrt} {\cyrv}{\cyrery}{\cyrv}{\cyro}{\cyrd} {\cyrf}{\cyro}{\cyrr}{\cyrm}{\cyru}{\cyrl}{\cyrery} {{\CYRL}{\cyro}{\cyrb}{\cyra}{\cyrch}{\cyre}{\cyrv}{\cyrs}{\cyrk}{\cyro}{\cyrg}{\cyro}} {\cyrd}{\cyrl}{\cyrya} {\cyru}{\cyrg}{\cyrl}{\cyra} {\cyrp}{\cyra}{\cyrr}{\cyra}{\cyrl}{\cyrl}{\cyre}{\cyrl}{\cyrsftsn}{\cyrn}{\cyro}{\cyrs}{\cyrt}{\cyri}}, journal = {Matematicheskoe Prosveshchenie}, pages = {255--256}, publisher = {mathdoc}, year = {1961}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/MP_1961_a22/} }
V. A. Efremovich. Наглядный вывод формулы Лобачевского для угла параллельности. Matematicheskoe Prosveshchenie, Математика, ее преподавание, приложения и история (1961), pp. 255-256. http://geodesic.mathdoc.fr/item/MP_1961_a22/