@misc{RCM_1968__2_251998,
     title = {[unknown]},
     journal = {Revista colombiana de matematicas},
     pages = {49--50},
     publisher = {mathdoc},
     volume = {2},
     year = {1968},
     url = {http://geodesic.mathdoc.fr/item/RCM_1968__2_251998/}
}