TY  - JOUR
AU  - John R. Stallings
TI  - A topological proof of Grushko's theorem on free products.
JO  - Mathematische Zeitschrift
PY  - 1965
SP  - 1
EP  - 8
VL  - 90
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/MZ_1965__90_170458/
ID  - MZ_1965__90_170458
ER  -