Voir la notice de l'article provenant de la source Math-Net.Ru
@article{MAT_1968_12_4_a2, author = {P. M. Neumann}, title = {On word subgroups of free groups}, journal = {Matematika}, pages = {25--41}, publisher = {mathdoc}, volume = {12}, number = {4}, year = {1968}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/MAT_1968_12_4_a2/} }
P. M. Neumann. On word subgroups of free groups. Matematika, Tome 12 (1968) no. 4, pp. 25-41. http://geodesic.mathdoc.fr/item/MAT_1968_12_4_a2/