1. E. Recami:Possible … and comments on tachyons, virtual particles, resonances, Report IFUM-088SM, University of Milano (August 1968), pages 4–8;Giornale di Fisica,10, 195 (1969), pages 203–205;V. S. Olkhovsky andE. Recami;Nuovo Cimento,63 A, 814 (1962), page 822. See also ref. (4).
2. See,e.g.,F. T. Hadjioannou:Nuovo Cimento,44, 185 (1966);I. Ferretti andM. Verde:Atti Accad. Scienze Torino (1966), page 318.
3. See also,E. C. G. Sudarshan:Ark. Phys.,39 (40), 5 5 (1969);Phys. Rev. D,1, 2428 (1970);A. M. Gleeson, M. G. Gundzig, E. C. G. Sudarshan andA. Pagnamenta:Particles and Nuclei,1, 1 (1970);Phys. Rev. A,6, 807 (1972);E. Van Der Spuy:Phys. Rev. D,7, 1106 (1973);C. Jue:Phys. Rev. D,8, 1757 (1973).
4. M. Baldo andE. Recami:Lett. Nuovo Cimento,2, 643 (1969), page 646;R. Mignani andE. Recami:Nuovo Cimento,30 A, 533 (1975), sect.4, pages 538–539;Phys. Lett.,65 B, 149 (1976), footnotes at page 149;E. Recami andR. Mignani:Phys. Lett.,62 B, 41 (1976), page 43;E. Recami, R. Mignani andG. Ziino: inRecent Development in Relativistic Q.F.T. and its Application, Vol.2 (Wroclaw, 1977), p. 269;M. Pavšič andE. Recami:Nuovo Cimento,36 A, 171 (1976), particularly footnotes (17,21,32).
5. H. C. Corben:Lett. Nuovo Cimento,20, 645 (1977); three preprints, Scarborough College, West Hill, Ontario (August, September and November 1977), submitted for publication; and inTachyons, monopoles, and Related Topics, edited byE. Recami (Amsterdam, 1978), to appear.