@article{GDZPPN002259516,
title = {A fundamental theorem in the theory of ruled surfaces},
journal = {Mathematische Annalen},
volume = {58},
year = {1904},
pages = {249-256},
url = {http://dml.mathdoc.fr/item/GDZPPN002259516}
}
Wilczynski, E.J. A fundamental theorem in the theory of ruled surfaces. Mathematische Annalen, Tome 58 (1904) pp. 249-256. http://gdmltest.u-ga.fr/item/GDZPPN002259516/