TY  - JOUR
AU  - JACOB NIELSEN
TI  - A basis for subgroups of free groups
JO  - Mathematica Scandinavica
PY  - 1955
SP  - 31
EP  - 43
VL  - 3
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/MS2_1955__3_165565/
ID  - MS2_1955__3_165565
ER  -