@misc{CMH_1971__46_186141,
     title = {[unknown]},
     journal = {Commentarii mathematici Helvetici},
     pages = {408--408},
     publisher = {mathdoc},
     volume = {46},
     year = {1971},
     url = {http://geodesic.mathdoc.fr/item/CMH_1971__46_186141/}
}