@misc{RCM_2008_42_2_a3,
     title = {On groups and normal polymorphic functions},
     journal = {Revista colombiana de matematicas},
     pages = {167--181},
     publisher = {mathdoc},
     volume = {42},
     number = {2},
     year = {2008},
     url = {http://geodesic.mathdoc.fr/item/RCM_2008_42_2_a3/}
}