TY  - JOUR
AU  - Timo Erkama
TI  - Group actions and extension problems for maps of balls
JO  - Annales Fennici Mathematici
PY  - 1973
VL  - 521-560
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/articles/10.5186/aasfm.1973.556/
DO  - 10.5186/aasfm.1973.556
LA  - en
ID  - AFM_1973_521-560_a4
ER  -