TY  - JOUR
AU  - Bergamasco, Adalberto P.
AU  - Zani, Sérgio Luís
TI  - Global Hypoellipticity of a Class of Second Order Operators
JO  - Canadian mathematical bulletin
PY  - 1994
SP  - 301
EP  - 305
VL  - 37
IS  - 3
UR  - http://geodesic.mathdoc.fr/articles/10.4153/CMB-1994-045-4/
DO  - 10.4153/CMB-1994-045-4
ID  - 10_4153_CMB_1994_045_4
ER  -