TY  - JOUR
AU  - S. Popa
TI  - Classification of subfactors: the reduction to commuting squares.
JO  - Inventiones mathematicae
PY  - 1990
SP  - 19
EP  - 44
VL  - 101
IS  - 2
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/IM_1990__101_2_143795/
ID  - IM_1990__101_2_143795
ER  -