@article{NAM_1896_3_15__491_1,
     author = {Appell, Paul},
     title = {Exercice sur les courbes de direction},
     journal = {Nouvelles annales de math\'ematiques : journal des candidats aux \'ecoles polytechnique et normale},
     pages = {491--495},
     publisher = {Carilian-Goeury et Vor Dalmont},
     volume = {3e s{\'e}rie, 15},
     year = {1896},
     language = {fr},
     url = {http://www.numdam.org/item/NAM_1896_3_15__491_1/}
}