@misc{RCM_1969__3_252012,
     title = {[unknown]},
     journal = {Revista colombiana de matematicas},
     pages = {23--24},
     publisher = {mathdoc},
     volume = {3},
     year = {1969},
     url = {http://geodesic.mathdoc.fr/item/RCM_1969__3_252012/}
}