@article{RCM_2012_46_1_a2,
     author = {Jhon J. BravoB and Diego F. Ruiz and Carlos A. Trujillo},
     title = {Cardinality of {Sets} {Associated} to {B3} and {B4} {Sets}},
     journal = {Revista colombiana de matematicas},
     pages = {27--37},
     publisher = {mathdoc},
     volume = {46},
     number = {1},
     year = {2012},
     url = {http://geodesic.mathdoc.fr/item/RCM_2012_46_1_a2/}
}