@article{GDZPPN002439905, title = {Strong positivity in C (...) for elliptic systems.}, journal = {Mathematische Zeitschrift}, volume = {209}, year = {1992}, pages = {251-272}, zbl = {0727.35045}, url = {http://dml.mathdoc.fr/item/GDZPPN002439905} }
Sweers, Guido. Strong positivity in C (...) for elliptic systems.. Mathematische Zeitschrift, Tome 209 (1992) pp. 251-272. http://gdmltest.u-ga.fr/item/GDZPPN002439905/