@article{RCM_1971__5_181589,
     author = {Carlos Ruiz Salguero and Roberto Ruiz},
     title = {La condicion de kann y la nocion de grupoide},
     journal = {Revista colombiana de matematicas},
     pages = {59--82},
     publisher = {mathdoc},
     volume = {5},
     year = {1971},
     url = {http://geodesic.mathdoc.fr/item/RCM_1971__5_181589/}
}