@article{CMUC_1993_34_2_a0,
     author = {Dr\'apal, Ale\v{s}},
     title = {On a class of commutative groupoids determined by their associativity triples},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {199--201},
     year = {1993},
     volume = {34},
     number = {2},
     mrnumber = {1241727},
     zbl = {0787.20040},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1993_34_2_a0/}
}