@article{GDZPPN002334852, title = {Covariant differential operators.}, journal = {Mathematische Annalen}, volume = {287}, year = {1990}, pages = {731-739}, zbl = {0723.22017}, url = {http://dml.mathdoc.fr/item/GDZPPN002334852} }
Enright, Thomas J.; Davidson, Mark G. Covariant differential operators.. Mathematische Annalen, Tome 287 (1990) pp. 731-739. http://gdmltest.u-ga.fr/item/GDZPPN002334852/