1. Osterwalder, K., Schrader, R.: Axioms for Euclidean Green's functions. Commun. math. Phys.31, 83 (1973)
2. Borchers, H.J.: On structure of the algebra of field operators. Nuovo Cimento24, 214 (1962)
3. Borchers, H.J.: Algebraic aspects of Wightman field theory. In: Sen, R.N., Weil, C. (Eds.): Statistical mechanics and field theory. New York: Halsted Press 1972
4. Wyss, W.: The field algebra and its positive linear functionals. Commun. math. Phys.27, 223 (1972)
5. Osterwalder, K.: Euclidean Green's functions and Wightman distributions. In: Velo, G., Wightman, A. (Eds.): Constructive quantum field theory, Vol. 25. Lecture Notes in Physics. Berlin-Heidelber-New York: Springer 1973