@article{JRAM_1970__242_151014,
     author = {Frank Levin},
     title = {On the laws of free nilpotent groups.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {108--114},
     publisher = {mathdoc},
     volume = {242},
     year = {1970},
     zbl = {0197.29803},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1970__242_151014/}
}