@article{AUPO_2011__50_1_a2,
     author = {Breen, Marilyn},
     title = {Sets {Expressible} as {Unions} of {Staircase} $n${-Convex} {Polygons}},
     journal = {Acta Universitatis Palackianae Olomucensis. Facultas Rerum Naturalium. Mathematica},
     pages = {23--28},
     publisher = {mathdoc},
     volume = {50},
     number = {1},
     year = {2011},
     mrnumber = {2920696},
     zbl = {1244.52009},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/AUPO_2011__50_1_a2/}
}