@article{NSJOM_1996_26_1a_8,
     author = {Crvenkovi\'c S. and Deli\'c D.},
     title = {Different levels of word problems for some varieties},
     journal = {Novi Sad Journal of Mathematics},
     pages = {93-102},
     year = {1996},
     volume = {26},
     number = {1},
     url = {http://geodesic.mathdoc.fr/item/NSJOM_1996_26_1a_8/}
}