@article{NSJOM_2002_32_2a_3,
     author = {Gh. 

 Ivan},
     title = {Special 

 morphism of groupoids},
     journal = {Novi Sad Journal of Mathematics},
     pages = {23-36},
     year = {2002},
     volume = {32},
     number = {2},
     url = {http://geodesic.mathdoc.fr/item/NSJOM_2002_32_2a_3/}
}