@article{GDZPPN002202352,
title = {Saddle surfaces admitting local support planes.},
journal = {Journal f\"ur die reine und angewandte Mathematik},
volume = {358},
year = {1985},
pages = {1-5},
zbl = {0551.53004},
url = {http://dml.mathdoc.fr/item/GDZPPN002202352}
}
Voloch, J.F.; Koutroufiotis, D. Saddle surfaces admitting local support planes.. Journal für die reine und angewandte Mathematik, Tome 358 (1985) pp. 1-5. http://gdmltest.u-ga.fr/item/GDZPPN002202352/