TY  - JOUR
AU  - I. P. Martynov
TI  - A generalization of a theorem of H. Wittich
JO  - Differencialʹnye uravneniâ
PY  - 1975
SP  - 388
EP  - 389
VL  - 11
IS  - 2
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1975_11_2_a22/
LA  - ru
ID  - DE_1975_11_2_a22
ER  -