@article{10.30755/NSJOM.09812,
     author = {Nitima Phrommarat and Sivaree Sudsanit},
     title = {On a product of universal relational systems},
     journal = {Novi Sad Journal of Mathematics},
     pages = {61 - 71},
     publisher = {mathdoc},
     volume = {50},
     number = {2},
     year = {2020},
     doi = {10.30755/NSJOM.09812},
     url = {http://geodesic.mathdoc.fr/articles/10.30755/NSJOM.09812/}
}