Voir la notice de l'article provenant de la source Novi sad journal of mathematics website
@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/} }
G. Čupona, S. Ilić. Free groupoids with x" = x II. Novi Sad Journal of Mathematics, Tome 29 (1999) no. 1. http://geodesic.mathdoc.fr/item/NSJOM_1999_29_1a_16/