@article{1077476909,
author = {Goldsmith, N. A.},
title = {Differential invariants of ruled surfaces belonging to one
special linear complex},
journal = {Duke Math. J.},
volume = {18},
number = {1},
year = {1951},
pages = { 831-836},
language = {en},
url = {http://dml.mathdoc.fr/item/1077476909}
}
Goldsmith, N. A. Differential invariants of ruled surfaces belonging to one
special linear complex. Duke Math. J., Tome 18 (1951) no. 1, pp. 831-836. http://gdmltest.u-ga.fr/item/1077476909/