TY  - JOUR
AU  - Cegielski, Andrzej
TI  - A generalization of the Opial's theorem
JO  - Control and Cybernetics
PY  - 2007
SP  - 601
EP  - 610
VL  - 36
IS  - 3
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/CC_2007_36_3_a8/
LA  - en
ID  - CC_2007_36_3_a8
ER  -