@article{NAM_1893_3_12__503_1,
     author = {Sondat, P.},
     title = {Sur un syst\`eme de coordonn\'ees triangulaires},
     journal = {Nouvelles annales de math\'ematiques : journal des candidats aux \'ecoles polytechnique et normale},
     pages = {503--519},
     publisher = {Carilian-Goeury et Vor Dalmont},
     volume = {3e s{\'e}rie, 12},
     year = {1893},
     language = {fr},
     url = {http://archive.numdam.org/item/NAM_1893_3_12__503_1/}
}