@article{JIS_2009__12_6_a5,
     author = {Mullen, Ryan},
     title = {On determining paint by numbers puzzles with nonunique solutions},
     journal = {Journal of integer sequences},
     publisher = {mathdoc},
     volume = {12},
     number = {6},
     year = {2009},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JIS_2009__12_6_a5/}
}