@article{MASLO_1989_39_3_a3,
     author = {\v{S}lapal, Josef},
     title = {On the direct power of relational systems},
     journal = {Mathematica slovaca},
     pages = {251--255},
     year = {1989},
     volume = {39},
     number = {3},
     mrnumber = {1016341},
     zbl = {0686.08001},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/MASLO_1989_39_3_a3/}
}