@article{JMPA_1847_1_12__343_0, author = {Bertrand, J.}, title = {Note sur la th\'eorie des normales \`a une m\^eme surface}, journal = {Journal de Math\'ematiques Pures et Appliqu\'ees}, pages = {343--346}, publisher = {Gauthier-Villars}, volume = {1e s{\'e}rie, 12}, year = {1847}, language = {fr}, url = {http://www.numdam.org/item/JMPA_1847_1_12__343_0/} }