@article{GDZPPN002289555,
title = {Hyperbolic surfaces of the form z == f (x, y).},
journal = {Mathematische Annalen},
volume = {142},
year = {1961},
pages = {77-79},
zbl = {0124.29103},
url = {http://dml.mathdoc.fr/item/GDZPPN002289555}
}
OSSERMAN, R. Hyperbolic surfaces of the form z == f (x, y).. Mathematische Annalen, Tome 142 (1961) pp. 77-79. http://gdmltest.u-ga.fr/item/GDZPPN002289555/