@article{1183416940, author = {Eisenhart, L. P.}, title = {Note on isotropic congruences}, journal = {Bull. Amer. Math. Soc.}, volume = {9}, number = {3}, year = {1902}, pages = { 301-303}, language = {en}, url = {http://dml.mathdoc.fr/item/1183416940} }
Eisenhart, L. P. Note on isotropic congruences. Bull. Amer. Math. Soc., Tome 9 (1902) no. 3, pp. 301-303. http://gdmltest.u-ga.fr/item/1183416940/