@article{BSMA_1880_2_4_1_317_1,
     author = {Gilbert, Ph.},
     title = {Extrait d'une lettre \`a {M.} {Darboux}},
     journal = {Bulletin des Sciences Math\'ematiques et Astronomiques},
     pages = {317--318},
     publisher = {Gauthier-Villars},
     volume = {2e s{\'e}rie, 4},
     number = {1},
     year = {1880},
     language = {fr},
     url = {http://archive.numdam.org/item/BSMA_1880_2_4_1_317_1/}
}