@article{NAM_1870_2_9__254_1,
     author = {Laguerre},
     title = {Extrait d'une lettre adress\'ee \`a {M.} {Bourget}},
     journal = {Nouvelles annales de math\'ematiques : journal des candidats aux \'ecoles polytechnique et normale},
     pages = {254--256},
     publisher = {Carilian-Goeury et Vor Dalmont},
     volume = {2e s{\'e}rie, 9},
     year = {1870},
     language = {fr},
     url = {http://www.numdam.org/item/NAM_1870_2_9__254_1/}
}