@article{RCM_1977__11_181667,
     author = {L. G. Torres},
     title = {Correcci\'on a: },
     journal = {Revista colombiana de matematicas},
     pages = {135--135},
     year = {1977},
     volume = {11},
     url = {http://geodesic.mathdoc.fr/item/RCM_1977__11_181667/}
}