@article{02033402, title = {On congruence classes of }, journal = {Novi Sad Journal of Mathematics}, volume = {28}, year = {1998}, pages = {75-89}, zbl = {1030.20503}, language = {en}, url = {http://dml.mathdoc.fr/item/02033402} }
Ušan, Janez. On congruence classes of . Novi Sad Journal of Mathematics, Tome 28 (1998) pp. 75-89. http://gdmltest.u-ga.fr/item/02033402/