1. Linear Operators;Dunford,1967
2. Quadratic forms and essential self-adjointness;Faris;Helv. Phys. Acta,1972
3. Invariant cones and uniqueness of the ground state for fermion systems;Faris;J. Math. Phys.,1972
4. Boson fields with non linear self-interaction in two dimensions;Glimm;Commun. Math. Phys.,1968
5. Existence and uniqueness of physical ground states;Gross;J. Functional Analysis,1972