@article{MAN_1978__237_182786,
     author = {Helmut Z\"oschinger},
     title = {Invarianten wesentlicher {\"Uberdeckungen.}},
     journal = {Mathematische Annalen},
     pages = {193--202},
     year = {1978},
     volume = {237},
     zbl = {0371.13009},
     url = {http://geodesic.mathdoc.fr/item/MAN_1978__237_182786/}
}