@article{GDZPPN002162539,
title = {On Halphen's Characteristic n, in the theory of Curves in Space.},
journal = {Journal f\"ur die reine und angewandte Mathematik},
volume = {112},
year = {1893},
pages = {347-352},
zbl = {25.1232.01},
url = {http://dml.mathdoc.fr/item/GDZPPN002162539}
}
Cayley, Arthur. On Halphen's Characteristic n, in the theory of Curves in Space.. Journal für die reine und angewandte Mathematik, Tome 112 (1893) pp. 347-352. http://gdmltest.u-ga.fr/item/GDZPPN002162539/