@article{SLC_1990_25_a14,
     author = {H. Weinhandl and Ewald Werner},
     title = {Two-colorings of the {Plane}},
     journal = {S\'eminaire lotharingien de combinatoire},
     year = {1990},
     volume = {25},
     url = {http://geodesic.mathdoc.fr/item/SLC_1990_25_a14/}
}