A Two Dimensional Fermi Liquid. Part 3: The Fermi Surface
  We show that the particle number density derived from the thermodynamic Green's function at temperature zero constructed in the second part of this series has a jump across the Fermi curve, a basic property of a Fermi liquid. We further show that the two particle thermodynamic Green's function at temperature zero has the regularity behavior expected in a Fermi liquid. 
Joel Feldman, Horst Knoerrer and Eugene Trubowitz