@article{SF_1993__47_2_135278,
     author = {I. Levi and S. Seif},
     title = {Range sets and partition sets in connection with congruences and algebraic invariants.},
     journal = {Semigroup forum},
     pages = {285--293},
     publisher = {mathdoc},
     volume = {47},
     number = {2},
     year = {1993},
     zbl = {0783.20036},
     url = {http://geodesic.mathdoc.fr/item/SF_1993__47_2_135278/}
}