@article{MZ_1950__52_169117,
     author = {E. BURGER},
     title = {\"Uber {Schnittzahlen} von {Homotopieketten}},
     journal = {Mathematische Zeitschrift},
     pages = {217--256},
     year = {1950},
     volume = {52},
     url = {http://geodesic.mathdoc.fr/item/MZ_1950__52_169117/}
}