Voir la notice de l'article provenant de la source European Digital Mathematics Library
@article{CMH_1952__26_139044, author = {Hans Wittich}, title = {Bemerkung zum {Typenproblem.}}, journal = {Commentarii mathematici Helvetici}, pages = {180--183}, publisher = {mathdoc}, volume = {26}, year = {1952}, zbl = {0049.06303}, url = {http://geodesic.mathdoc.fr/item/CMH_1952__26_139044/} }
Hans Wittich. Bemerkung zum Typenproblem.. Commentarii mathematici Helvetici, Tome 26 (1952), pp. 180-183. http://geodesic.mathdoc.fr/item/CMH_1952__26_139044/