@article{GDZPPN002444690,
title = {A non uniqueness result for operators of principle type.},
journal = {Mathematische Zeitschrift},
volume = {220},
year = {1995},
pages = {561-568},
zbl = {0851.35003},
url = {http://dml.mathdoc.fr/item/GDZPPN002444690}
}
Baouendi, M.S.; Alinhac, S. A non uniqueness result for operators of principle type.. Mathematische Zeitschrift, Tome 220 (1995) pp. 561-568. http://gdmltest.u-ga.fr/item/GDZPPN002444690/