1. G. P. Beretta, E. P. Gyftopoulos, J. L. Park andG. N. Hatsopoulos:Nuovo Cimento B,82, 169 (1984).
2. R. Jancel:Foundations of Classical and Quantum Statistical Mechanics (Pergamon Press, Oxford, 1969).
3. G. N. Hatsopoulos andE. P. Gyftopoulos:Found. Phys.,6, 15, 127, 439, 561 (1976).
4. If |ϕ> is an eigenvector of the idempotent quantum-mechanical state operatorP (P 2=P), such thatP|ϕ>=|ϕ> and <ϕ|ϕ>=1, thenP=|ϕ><ϕ| and |ϕ> is the quantum-mechanical state vector
5. See,e. g.,R. Jancel:Foundations of Classical and Quantum Statistical Mechanics (Pergamon Press, Oxford, 1969);J. Mehra andE. C. G. Sudarshan:Nuovo Cimento B,11, 215 (1972);R. S. Ingarden andA. Kossakowski:Ann. Phys.,89, 451 (1975);J. L. Park andW. Band:Found. Phys.,8, 239 (1978);A. Wehrl:Rev. Mod. Phys.,50, 221 (1978), and references therein.