@article{1102779974, author = {Ramsay, Arlan}, title = {Subobjects of virtual groups.}, journal = {Pacific J. Math.}, volume = {91}, number = {2}, year = {1980}, pages = { 389-454}, language = {en}, url = {http://dml.mathdoc.fr/item/1102779974} }
Ramsay, Arlan. Subobjects of virtual groups.. Pacific J. Math., Tome 91 (1980) no. 2, pp. 389-454. http://gdmltest.u-ga.fr/item/1102779974/