@article{BAG_1989__29_138447,
     author = {W. M\"ogling},
     title = {\"Uber {Trapezen} umbeschriebene rechtwinklige {Dreiecke}},
     journal = {Beitr\"age zur Algebra und Geometrie},
     pages = {161--170},
     publisher = {mathdoc},
     volume = {29},
     year = {1989},
     zbl = {0705.52012},
     url = {http://geodesic.mathdoc.fr/item/BAG_1989__29_138447/}
}