@article{MZ_1970__117_171422,
     author = {Norman Blackburn},
     title = {The {Extension} {Theory} of the {Symmetric} and {Alternating} {Groups.}},
     journal = {Mathematische Zeitschrift},
     pages = {191--206},
     publisher = {mathdoc},
     volume = {117},
     year = {1970},
     zbl = {0205.32401},
     url = {http://geodesic.mathdoc.fr/item/MZ_1970__117_171422/}
}