@article{JMPA_1848_1_13__73_0,
     author = {Bertrand, J.},
     title = {D\'emonstration g\'eom\'etrique de quelques th\'eor\`emes relatifs \`a la th\'eorie des surfaces},
     journal = {Journal de Math\'ematiques Pures et Appliqu\'ees},
     pages = {73--79},
     publisher = {Gauthier-Villars},
     volume = {1e s{\'e}rie, 13},
     year = {1848},
     language = {fr},
     url = {http://www.numdam.org/item/JMPA_1848_1_13__73_0/}
}