@article{MZ_1923__18_167744,
     author = {E. Bilz},
     title = {Beitrag zu den {Grundlagen} der kombinatorischen {Analysis} situs},
     journal = {Mathematische Zeitschrift},
     pages = {1--41},
     year = {1923},
     volume = {18},
     zbl = {49.0398.02},
     url = {http://geodesic.mathdoc.fr/item/MZ_1923__18_167744/}
}