TY  - JOUR
AU  - Karrass, A.
AU  - Pietrowski, A.
AU  - Solitar, D.
TI  - An Improved Subgroup Theorem for HNN Groups with Some Applications
JO  - Canadian journal of mathematics
PY  - 1974
SP  - 214
EP  - 224
VL  - 26
IS  - 1
UR  - http://geodesic.mathdoc.fr/articles/10.4153/CJM-1974-021-1/
DO  - 10.4153/CJM-1974-021-1
ID  - 10_4153_CJM_1974_021_1
ER  -