@article{CMUC_1989_30_2_a2,
     author = {Pu\v{s}, Vladim{\'\i}r},
     title = {Representation of semigroups by products of simple graphs},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {227--234},
     year = {1989},
     volume = {30},
     number = {2},
     mrnumber = {1014122},
     zbl = {0678.05060},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1989_30_2_a2/}
}