@article{1214428824,
author = {Ambrose, W.},
title = {Convexity of partial differential operators},
journal = {J. Differential Geom.},
volume = {3},
number = {1-2},
year = {1969},
pages = { 125-164},
language = {en},
url = {http://dml.mathdoc.fr/item/1214428824}
}
Ambrose, W. Convexity of partial differential operators. J. Differential Geom., Tome 3 (1969) no. 1-2, pp. 125-164. http://gdmltest.u-ga.fr/item/1214428824/