@article{MAN_1981__256_163501,
     author = {Ragni Piene},
     title = {Cuspidal {Projections} of {Space} {Curves.}},
     journal = {Mathematische Annalen},
     pages = {95--120},
     year = {1981},
     volume = {256},
     zbl = {0468.14010},
     url = {http://geodesic.mathdoc.fr/item/MAN_1981__256_163501/}
}