@article{GDZPPN00218480X, title = {On the laws of free nilpotent groups.}, journal = {Journal f\"ur die reine und angewandte Mathematik}, volume = {244}, year = {1970}, pages = {108-114}, zbl = {0197.29803}, url = {http://dml.mathdoc.fr/item/GDZPPN00218480X} }
Levin, Frank. On the laws of free nilpotent groups.. Journal für die reine und angewandte Mathematik, Tome 244 (1970) pp. 108-114. http://gdmltest.u-ga.fr/item/GDZPPN00218480X/