@article{GDZPPN002407523, title = {The Extension Theory of the Symmetric and Alternating Groups.}, journal = {Mathematische Zeitschrift}, volume = {114}, year = {1970}, pages = {191-206}, zbl = {0205.32401}, url = {http://dml.mathdoc.fr/item/GDZPPN002407523} }
Blackburn, Norman. The Extension Theory of the Symmetric and Alternating Groups.. Mathematische Zeitschrift, Tome 114 (1970) pp. 191-206. http://gdmltest.u-ga.fr/item/GDZPPN002407523/