@article{JGG_2003_7_2_JGG_2003_7_2_a4,
     author = {S. Wilson and A. Breda d'Azevedo},
     title = {Non-orientable {Maps} and {Hypermaps} with {Few} {Faces}},
     journal = {Journal for geometry and graphics},
     pages = {173--19},
     publisher = {mathdoc},
     volume = {7},
     number = {2},
     year = {2003},
     url = {http://geodesic.mathdoc.fr/item/JGG_2003_7_2_JGG_2003_7_2_a4/}
}