Voir la notice de l'article provenant de la source Novi sad journal of mathematics website
@article{NSJOM_1998_28_1a_6, author = {J. U\v{s}an}, title = {On congruence classes of n-groups}, journal = {Novi Sad Journal of Mathematics}, pages = {75-89}, publisher = {mathdoc}, volume = {28}, number = {1}, year = {1998}, url = {http://geodesic.mathdoc.fr/item/NSJOM_1998_28_1a_6/} }
J. Ušan. On congruence classes of n-groups. Novi Sad Journal of Mathematics, Tome 28 (1998) no. 1. http://geodesic.mathdoc.fr/item/NSJOM_1998_28_1a_6/