TY  - JOUR
AU  - Andrzej Zajtz
TI  - On the order of natural differential operators and liftings
JO  - Annales Polonici Mathematici
PY  - 1988
SP  - 169
EP  - 178
VL  - 49
IS  - 2
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/articles/10.4064/ap-49-2-169-178/
DO  - 10.4064/ap-49-2-169-178
LA  - en
ID  - 10_4064_ap_49_2_169_178
ER  -