@article{10_4064_cm_29_1_83_85,
     author = {Ernest P{\l}onka},
     title = {Idempotent words in nilpotent groups},
     journal = {Colloquium Mathematicum},
     pages = {83--85},
     publisher = {mathdoc},
     volume = {29},
     number = {1},
     year = {1974},
     doi = {10.4064/cm-29-1-83-85},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm-29-1-83-85/}
}