@article{MZ_1943__49_169033,
     author = {G. Bol},
     title = {\"Uber {Nabelpunkte} auf einer {Eifl\"ache}},
     journal = {Mathematische Zeitschrift},
     pages = {389--410},
     publisher = {mathdoc},
     volume = {49},
     year = {1943},
     language = {de},
     url = {http://geodesic.mathdoc.fr/item/MZ_1943__49_169033/}
}