TY  - JOUR
AU  - Yu. V. Egorov
TI  - Necessary conditions for the solvability of pseudodifferential equations of principal type
JO  - Trudy Moskovskogo matematičeskogo obŝestva
PY  - 1971
SP  - 29
EP  - 41
VL  - 24
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/MMO_1971_24_a1/
LA  - ru
ID  - MMO_1971_24_a1
ER  -