TY  - JOUR
AU  - A. T. Fomenko
AU  - H. Zieschang
TI  - A topological invariant and a criterion for the equivalence of integrable Hamiltonian systems with two degrees of freedom
JO  - Izvestiya. Mathematics 
PY  - 1991
SP  - 567
EP  - 596
VL  - 36
IS  - 3
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/IM2_1991_36_3_a5/
LA  - en
ID  - IM2_1991_36_3_a5
ER  -