@article{GDZPPN002394731, title = {Schreier varieties of groups.}, journal = {Mathematische Zeitschrift}, volume = {85}, year = {1964}, pages = {392-400}, zbl = {0126.26901}, url = {http://dml.mathdoc.fr/item/GDZPPN002394731} }
Wiegold, James; Neumann, Peter M. Schreier varieties of groups.. Mathematische Zeitschrift, Tome 85 (1964) pp. 392-400. http://gdmltest.u-ga.fr/item/GDZPPN002394731/