@article{01930464, title = {Levi's parametrix for some sub-elliptic non-divergence form operators.}, journal = {Electronic Research Announcements of the American Mathematical Society [electronic only]}, volume = {9}, year = {2003}, pages = {10-18}, doi = {10.1090/S1079-6762-03-00107-0}, zbl = {1015.35034}, language = {en}, url = {http://dml.mathdoc.fr/item/01930464} }
Bonfiglioli, Andrea; Lanconelli, Ermanno; Uguzzoni, Francesco. Levi's parametrix for some sub-elliptic non-divergence form operators.. Electronic Research Announcements of the American Mathematical Society [electronic only], Tome 9 (2003) pp. 10-18. doi : 10.1090/S1079-6762-03-00107-0. http://gdmltest.u-ga.fr/item/01930464/