@article{GDZPPN00243606X,
title = {A Class of Globally Hypoelliptic Operators on the Torus.},
journal = {Mathematische Zeitschrift},
volume = {202},
year = {1989},
pages = {1-12},
zbl = {0644.35027},
url = {http://dml.mathdoc.fr/item/GDZPPN00243606X}
}
Yoshino, Masafumi. A Class of Globally Hypoelliptic Operators on the Torus.. Mathematische Zeitschrift, Tome 202 (1989) pp. 1-12. http://gdmltest.u-ga.fr/item/GDZPPN00243606X/