@article{GDZPPN002423707, title = {Quasi Fricke Polygons and the Nielsen Convex Region.}, journal = {Mathematische Zeitschrift}, volume = {174}, year = {1980}, pages = {239-244}, zbl = {0417.30038}, url = {http://dml.mathdoc.fr/item/GDZPPN002423707} }
Purzitsky, Norman. Quasi Fricke Polygons and the Nielsen Convex Region.. Mathematische Zeitschrift, Tome 174 (1980) pp. 239-244. http://gdmltest.u-ga.fr/item/GDZPPN002423707/