1. S Albeverio and R Hoegh-Krohn, Uniqueness of the physical vacuum and the Wightman functions in the infinite volume limit for some non-polynomial interactions, Commun. Math. Phys. 30, 171–200 (1973)
2. S Albeverio and R Hoegh-Krohn, The scattering matrix for some non-polynomial interactions, I and II, Helv., Phys. Acta, to appear
3. S Albeverio and R Hoegh-Krohn, The Wightman axioms and the mass gap for strong interactions of exponential type in two dimensional space-time, Oslo reprint
4. S Albeverio and R Hoegh-Krohn, Asymptotic series for the scattering operator and asymptotic unitarity of the space cut-off interactions, Oslo preprint.
5. R Baumel, Private communication, see also [GuRoSi 3]