Voir la notice de l'article provenant de la source Math-Net.Ru
@article{AL_1996_35_2_a2, author = {Yu. L. Ershov}, title = {Free $\Delta^*$-groups}, journal = {Algebra i logika}, pages = {154--172}, publisher = {mathdoc}, volume = {35}, number = {2}, year = {1996}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/AL_1996_35_2_a2/} }
Yu. L. Ershov. Free $\Delta^*$-groups. Algebra i logika, Tome 35 (1996) no. 2, pp. 154-172. http://geodesic.mathdoc.fr/item/AL_1996_35_2_a2/