@article{MAN_1963__151_161071,
     author = {G. Burde},
     title = {Zur {Theorie} der {Z\"opfe.}},
     journal = {Mathematische Annalen},
     pages = {101--107},
     publisher = {mathdoc},
     volume = {151},
     year = {1963},
     zbl = {0112.38604},
     url = {http://geodesic.mathdoc.fr/item/MAN_1963__151_161071/}
}