@article{CMH_1962__37_139256,
     author = {Christian Blatter},
     title = {\"Uber ein {Typenproblem.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {198--213},
     publisher = {mathdoc},
     volume = {37},
     year = {1962},
     url = {http://geodesic.mathdoc.fr/item/CMH_1962__37_139256/}
}