TY  - JOUR
AU  - Solomon Lefschetz
TI  - Complete families of periodic solutions of differential equations.
JO  - Commentarii mathematici Helvetici
PY  - 1954
SP  - 341
EP  - 345
VL  - 28
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/CMH_1954__28_139089/
ID  - CMH_1954__28_139089
ER  -