@article{bwmeta1.element.bwnjournal-article-fmv97i1p11bwm,
author = {Ernest P\l onka},
title = {Symmetric words in nilpotent groups of class $\leq$ 3},
journal = {Fundamenta Mathematicae},
volume = {96},
year = {1977},
pages = {95-103},
zbl = {0383.20018},
language = {en},
url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-fmv97i1p11bwm}
}
Płonka, Ernest. Symmetric words in nilpotent groups of class ≤ 3. Fundamenta Mathematicae, Tome 96 (1977) pp. 95-103. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-fmv97i1p11bwm/