Completely Integrable Contact Hamiltonian Systems and Toric Contact   Structures on $S^2\times S^3$
  I begin by giving a general discussion of completely integrable Hamiltonian systems in the setting of contact geometry. We then pass to the particular case of toric contact structures on the manifold $S^2\times S^3$. In particular we give a complete solution to the contact equivalence problem for a class of toric contact structures, $Y^{p,q}$, discovered by physicists by showing that $Y^{p,q}$ and $Y^{p',q'}$ are inequivalent as contact structures if and only if $p\neq p'$. 
Charles P. Boyer
math.SG math-ph math.DG math.MP