@article{CMUC_1983_24_4_a4,
     author = {P{\l}onka, Jerzy},
     title = {Subdirectly irreducible groupoids in some varieties},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {631--645},
     year = {1983},
     volume = {24},
     number = {4},
     mrnumber = {738559},
     zbl = {0543.08007},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1983_24_4_a4/}
}