@article{RCM_1968__2_181568,
     author = {Nello Allan},
     title = {Algunos grupos aritm\'eticos no maximales},
     journal = {Revista colombiana de matematicas},
     pages = {169--171},
     publisher = {mathdoc},
     volume = {2},
     year = {1968},
     url = {http://geodesic.mathdoc.fr/item/RCM_1968__2_181568/}
}