1. W. Buchmüller: Acta. Phys. Austriaca Suppl. XXVII (1985) 517
2. M.E. Peskin: Proc. of the int. symp. on lepton and photon interactions at high energies, Kyoto, 1985, p. 713 eds. M. Konuma, K. Takahashi: Kyoto: Kyoto University 1986
3. H. Harari: Proc. of the 5th topical workshop on protonantiproton collider physics, Saint-Vincent, Aosta Valley, 1985, p. 429 ed. M. Greco. Singapore: World Scientific 1985
4. K. Abe et al.: Phys. Lett. B232 (1989) 425
5. H. Kroha: contributed paper to the 25th International Conference on High Energy Physics, Singapore, August 2–8, 1990