@article{VM_2004_6_3_a1,
     author = {G. Lucca},
     title = {Symmetrical {Patterns} by {Means} of {Contour} {Plots}},
     journal = {Visual Mathematics},
     publisher = {mathdoc},
     volume = {6},
     number = {3},
     year = {2004},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/VM_2004_6_3_a1/}
}