1. Some of these works are Surdin (1971a, b), de la Peña and Cetto (1977c, 1978, 1985a, 1986).
2. We borrow the expression from Moore (1983a), where a similar point of view is firmly advocated. The same possibility is expressed in Theimer and Peterson (1977) (and afterwards by Theimer alone on repeated occasions), Pesquera and Claverie (1982), and de la Pefia (1983, p. 563), while in Santos (1981) a modification of the zeropoint spectrum by matter is considered as a means of avoiding the Bell inequalities.
3. Preliminary and partial discussions of the theory under review are given in Cetto and de la Peña (1991a, b) and de la Peña and Cetto (1991–1995).
4. The solution to this problem is discussed in §10.3.3.
5. A. Jáuregui (unfinished manuscript of 1991–92) has initiated a study along these lines for the harmonic oscillator in a magnetic field.