@article{ELMA_1979__34_141237,
     author = {R. Powarzynski and H. Spiegel},
     title = {\"Uber zwei besondere {Eigenschaften} von {Dreiecksfl\"achnernetzen.}},
     journal = {Elemente der Mathematik},
     pages = {140--146},
     publisher = {mathdoc},
     volume = {34},
     year = {1979},
     zbl = {0435.51015},
     url = {http://geodesic.mathdoc.fr/item/ELMA_1979__34_141237/}
}