@article{JMPA_1928_9_7__337_0,
     author = {P\'er\`es, Joseph},
     title = {Sur la condition des travaux virtuels},
     journal = {Journal de Math\'ematiques Pures et Appliqu\'ees},
     pages = {337--343},
     publisher = {Gauthier-Villars},
     volume = {9e s{\'e}rie, 7},
     year = {1928},
     language = {fr},
     url = {http://www.numdam.org/item/JMPA_1928_9_7__337_0/}
}