@article{MZ_1968__104_170931,
     author = {Olaf Tamaschke},
     title = {An {Extension} of {Group} {Theory} to {S-semigroups.}},
     journal = {Mathematische Zeitschrift},
     pages = {74--90},
     year = {1968},
     volume = {104},
     zbl = {0155.04702},
     url = {http://geodesic.mathdoc.fr/item/MZ_1968__104_170931/}
}