@article{CMH_1934__6_138612,
     author = {Arnold Emch},
     title = {Ueber symmetrische {Monoide} und {Kegel.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {133--143},
     publisher = {mathdoc},
     volume = {6},
     year = {1934},
     zbl = {0007.32305},
     url = {http://geodesic.mathdoc.fr/item/CMH_1934__6_138612/}
}