@article{VM_2008_10_3_a4,
     author = {Jonathan P. Keiter},
     title = {The {Projection} {Sphere}},
     journal = {Visual Mathematics},
     publisher = {mathdoc},
     volume = {10},
     number = {3},
     year = {2008},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/VM_2008_10_3_a4/}
}