@article{NSJOM_1999_29_1a_16,
     author = {G. 

 \v{C}upona, S. Ili\'c},
     title = {Free 

 groupoids with x" = x {II}},
     journal = {Novi Sad Journal of Mathematics},
     pages = {147-154},
     publisher = {mathdoc},
     volume = {29},
     number = {1},
     year = {1999},
     url = {http://geodesic.mathdoc.fr/item/NSJOM_1999_29_1a_16/}
}