@article{IM2_1988_31_2_a7,
     author = {S. L. Ziglin},
     title = {Splitting of the separatrices and the nonexistence of first integrals in systems of differential equations of {Hamiltonian} type with two degrees of freedom},
     journal = {Izvestiya. Mathematics },
     pages = {407--421},
     publisher = {mathdoc},
     volume = {31},
     number = {2},
     year = {1988},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1988_31_2_a7/}
}