@article{NSJOM_2004_34_2a_4,
     author = {M. Demlov\'{a} and V. Koubek},
     title = {Weaker 

 universalities in semigroup varieties},
     journal = {Novi Sad Journal of Mathematics},
     pages = {37-86},
     year = {2004},
     volume = {34},
     number = {2},
     url = {http://geodesic.mathdoc.fr/item/NSJOM_2004_34_2a_4/}
}