@article{VM_1999_1_1_a1,
     author = {Douglas Dunham},
     title = {Transformation of {Hyperbolic} {Escher} {Patterns}},
     journal = {Visual Mathematics},
     publisher = {mathdoc},
     volume = {1},
     number = {1},
     year = {1999},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/VM_1999_1_1_a1/}
}