@article{RCM_1975__9_181636,
     author = {Harold Bell},
     title = {A note on universal maps},
     journal = {Revista colombiana de matematicas},
     pages = {91--94},
     publisher = {mathdoc},
     volume = {9},
     year = {1975},
     zbl = {0321.55020},
     url = {http://geodesic.mathdoc.fr/item/RCM_1975__9_181636/}
}