1. A review of the field is presented in the article byM. Surdin:Ann. Inst. H. Poincaré,15, 203 (1971). New developments and farther references are given byE. Santos:Lett. Nuovo Cimento,4, 497 (1972).
2. T. W. Marshall:Proc. Cambridge Phil. Soc.,61, 537 (1965);T. H. Boyer:Phys. Rev.,182, 1374 (1969).
3. E. Santos:Brownian motion and the stochastic theory of quantum mechanics, in Irreversibilityin the Many-Body Problem, edited byL. M. Garrido,J. Biel andJ. Eea (New York, 1972). Standard references are:E. Nelson:Phys. Rev.,150, B 1079 (1966);
4. L. de la Peña-Auerbach:Journ. Math. Phys.,10, 1620 (1969).
5. M. Surdin:Intern. Journ. Theor. Phys.,4, 117 (1971).