1. Mack, G.: Group theoretical approach to CQFT. In: Renormalization and invariance in QFT (E. R. Caianello, ed.). New York: Plenum Press 1974
2. Dobrev, V. K., Mack, G., Petkova, V. B., Petrova, S. G., Todorov, I. T.: On the Clebsch-Gordon expansion for the Lorentz group inn dimensions, IAS Preprint, Princeton (1975)
3. Mack, G.: Lecture Notes in Physics 37 (H. Rollnik, K. Dietz, eds.), pp. 66. Berlin-Heidelberg-New York: Springer 1975
4. Dobrev, V. K., Petkova, V. B., Petrova, S. G., Todorov, I. T.: Dynamical derivation of vacuum operator product expansions in euclidean conformal quantum field theory, Preprint (1975)
5. This problem was also investigated by Schroer, B., Swieca, J. A., Völkel, A. H.: Phys. Rev.D11, 1509 (1975)