@article{NSJOM_1999_29_2a_8,
     author = {G. 

 \v{C}upona and N. Celakoski and B. Janeva},
     title = {Free 

 groupoids with axioms of the form x^(m+1)y = xy and/or xy^(n+l) = xy},
     journal = {Novi Sad Journal of Mathematics},
     pages = {131-147},
     publisher = {mathdoc},
     volume = {29},
     number = {2},
     year = {1999},
     url = {http://geodesic.mathdoc.fr/item/NSJOM_1999_29_2a_8/}
}