@article{MAN_1938__115_159980,
     author = {H. Cremer},
     title = {\"Uber die {H\"aufigkeit} der {Nichtzentren.}},
     journal = {Mathematische Annalen},
     pages = {573--580},
     year = {1938},
     volume = {115},
     zbl = {0018.36802},
     url = {http://geodesic.mathdoc.fr/item/MAN_1938__115_159980/}
}