TY  - JOUR
AU  - Karsten Grove
AU  - Detlef Gromoll
TI  - On Metrics on S2 All of Whose Geodesics Are Closed.
JO  - Inventiones mathematicae
PY  - 1981
SP  - 175
EP  - 178
VL  - 65
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/IM_1981__65_142845/
ID  - IM_1981__65_142845
ER  -