@article{MZ_1989__202_1_174108,
     author = {Irene Zimmermann},
     title = {Submodular {Subgroups} in {Finite} {Groups.}},
     journal = {Mathematische Zeitschrift},
     pages = {545--558},
     year = {1989},
     volume = {202},
     number = {1},
     zbl = {0704.20018},
     url = {http://geodesic.mathdoc.fr/item/MZ_1989__202_1_174108/}
}