@article{BAG_1991__31_138473,
     author = {H.-D. Hecker and U. Ahlfeld},
     title = {Eine {Hierarchie} einfacher {Polygone}},
     journal = {Beitr\"age zur Algebra und Geometrie},
     pages = {45--56},
     publisher = {mathdoc},
     volume = {31},
     year = {1991},
     language = {de},
     url = {http://geodesic.mathdoc.fr/item/BAG_1991__31_138473/}
}