@article{05237145,
title = {Liouville theorems for a class of linear second-order operators with nonnegative characteristic form.},
journal = {Boundary Value Problems [electronic only]},
volume = {2007},
year = {2007},
doi = {10.1155/2007/48232},
zbl = {1158.35338},
language = {en},
url = {http://dml.mathdoc.fr/item/05237145}
}
Kogoj, Alessia Elisabetta; Lanconelli, Ermanno. Liouville theorems for a class of linear second-order operators with nonnegative characteristic form.. Boundary Value Problems [electronic only], Tome 2007 (2007) . doi : 10.1155/2007/48232. http://gdmltest.u-ga.fr/item/05237145/