TY  - JOUR
AU  - F. H. Szafraniec
TI  - Note on the existence of periodic solutions of a second order differential equation
JO  - Annales Polonici Mathematici
PY  - 1968
SP  - 305
EP  - 307
VL  - 21
IS  - 3
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/articles/10.4064/ap-21-3-305-307/
DO  - 10.4064/ap-21-3-305-307
LA  - en
ID  - 10_4064_ap_21_3_305_307
ER  -