K. Nakagawa et H. Yoshida, A necessary condition for the integrability of homogeneous Hamiltonian systems with two degrees of freedom, J PHYS A, 34(11), 2001, pp. 2137-2148
A necessary condition for the integrability of Hamiltonian systems with a t
wo-dimensional homogeneous potential, due to Morales-Ruiz and Ramis, is ext
ended for more general Hamiltonian systems of the form H = T(p) + V(q), wit
h homogeneous functions T(p) and V(q).