@article{JRAM_1929__160_149678,
     author = {Heinrich Tietze},
     title = {Bemerkungen \"uber konvexe und nicht-konvexe {Figuren.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {67--69},
     publisher = {mathdoc},
     volume = {160},
     year = {1929},
     zbl = {55.0433.01},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1929__160_149678/}
}