@article{GDZPPN002413272, title = {Normal Subgroups of M-Groups Need Not Be M-Groups.}, journal = {Mathematische Zeitschrift}, volume = {135}, year = {1973}, pages = {313-318}, zbl = {0255.20007}, url = {http://dml.mathdoc.fr/item/GDZPPN002413272} }
Dade, Everett C. Normal Subgroups of M-Groups Need Not Be M-Groups.. Mathematische Zeitschrift, Tome 135 (1973) pp. 313-318. http://gdmltest.u-ga.fr/item/GDZPPN002413272/