Realizability of singular levels of Morse functions by unions of   geodesics
  We list special graphs of degree 4 with at most 3 vertices (atoms from the theory of integrable hamiltonian systems) which could be represented by a union of closed geodesics on the one of the following surfaces with metric of constant curvature: sphere, projective plane, torus, Klein bottle. 
I. Shnurnikov
math.AT math.GT