@article{GDZPPN002430800,
title = {Any Hermitian Metric of Constant Non-Positive (Hermitian) Holomorphic Sectional Curvature on a Compact Complex Surface is K\"ahler.},
journal = {Mathematische Zeitschrift},
volume = {189},
year = {1985},
pages = {39-44},
zbl = {0549.53063},
url = {http://dml.mathdoc.fr/item/GDZPPN002430800}
}
Gauduchon, Paul; Balas, Andrew. Any Hermitian Metric of Constant Non-Positive (Hermitian) Holomorphic Sectional Curvature on a Compact Complex Surface is Kähler.. Mathematische Zeitschrift, Tome 189 (1985) pp. 39-44. http://gdmltest.u-ga.fr/item/GDZPPN002430800/