@article{JMPA_1888_4_4__129_0,
     author = {Humbert, G.},
     title = {Sur les courbes cycliques de direction},
     journal = {Journal de Math\'ematiques Pures et Appliqu\'ees},
     pages = {129--131},
     publisher = {Gauthier-Villars},
     volume = {4e s{\'e}rie, 4},
     year = {1888},
     language = {fr},
     url = {http://www.numdam.org/item/JMPA_1888_4_4__129_0/}
}