1. P. R. Johnson, Ph.D. thesis, University of Maryland, College Park, 1999 (unpublished).
2. P. R. Johnson and B. L. Hu, Stochastic theory of relativistic particles moving in a quantum field: influence functional and Langevin equation [quant-ph/0012137].
3. E. B. Davies, The Quantum Theory of Open Systems (Academic, London, 1976); U. Weiss, Quantum Dissipative Systems (World Scientific, Singapore, 1993).
4. A. O. Caldeira and A. J. Leggett, Physica A 121, 587 (1983);
5. Ann. Phys. (N.Y.) 149, 374 (1983);