@article{SD_1954-1955__8__A10_0,
     author = {Petresco, J.},
     title = {Sur les groupes libres. {I} - {Identit\'e} ; th\'eor\`eme de {Nielsen-Schreier}},
     journal = {S\'eminaire Dubreil. Alg\`ebre et th\'eorie des nombres},
     note = {talk:21},
     pages = {1--12},
     publisher = {Secr\'etariat math\'ematique},
     volume = {8},
     year = {1954-1955},
     language = {fr},
     url = {http://www.numdam.org/item/SD_1954-1955__8__A10_0/}
}