Voir la notice de l'article provenant de la source European Digital Mathematics Library
@article{MI_1975__10_3_189304, author = {{\CYRI}.{\CYRA}. {\CYRG}{\cyro}{\cyrl}{\cyro}{\cyrv}{\cyrk}{\cyro}}, title = {$pi$-{\cyrg}{\cyrr}{\cyru}{\cyrp}{\cyrp}{\cyro}{\cyri}{\cyrd}{\cyrery} {\cyri} $pi$-{\cyrs}{\cyre}{\cyrt}{\cyri}}, journal = {Matemati\v{c}eskie issledovani\^a}, pages = {29--43}, publisher = {mathdoc}, volume = {10}, number = {3}, year = {1975}, zbl = {0357.20035}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/MI_1975__10_3_189304/} }
И.А. Головко. $pi$-группоиды и $pi$-сети. Matematičeskie issledovaniâ, Tome 10 (1975) no. 3, pp. 29-43. http://geodesic.mathdoc.fr/item/MI_1975__10_3_189304/