@article{NAM_1879_2_18__201_0,
     author = {de Saint-Germain, A.},
     title = {Lignes de courbure de la surface $z = L \cos y - L \cos x$},
     journal = {Nouvelles annales de math\'ematiques : journal des candidats aux \'ecoles polytechnique et normale},
     pages = {201--203},
     publisher = {Carilian-Goeury et Vor Dalmont},
     volume = {2e s{\'e}rie, 18},
     year = {1879},
     language = {fr},
     url = {http://www.numdam.org/item/NAM_1879_2_18__201_0/}
}