@article{GDZPPN002435500,
title = {On Pt\'ak's Generalization of the Open-Mapping and Closed-Graph Theorems.},
journal = {Mathematische Zeitschrift},
volume = {199},
year = {1988},
pages = {399-406},
zbl = {0643.46004},
url = {http://dml.mathdoc.fr/item/GDZPPN002435500}
}
DeVito, Carl L. On Pták's Generalization of the Open-Mapping and Closed-Graph Theorems.. Mathematische Zeitschrift, Tome 199 (1988) pp. 399-406. http://gdmltest.u-ga.fr/item/GDZPPN002435500/