@article{DAN_1963_153_5_a7,
     author = {H. Zieschang},
     title = {On a problem of {Neuwirth} on knot groups},
     journal = {Doklady Akademii Nauk},
     pages = {1017--1019},
     publisher = {mathdoc},
     volume = {153},
     number = {5},
     year = {1963},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1963_153_5_a7/}
}