@article{10_4064_cm_21_1_35_37,
     author = {J. P{\l}onka},
     title = {On the arity of idempotent reducts of groups},
     journal = {Colloquium Mathematicum},
     pages = {35--37},
     publisher = {mathdoc},
     volume = {21},
     number = {1},
     year = {1970},
     doi = {10.4064/cm-21-1-35-37},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm-21-1-35-37/}
}