1. See f.i. Toner, W.T.: Lepton-Hadron Interactions. Proc. of the 4th Int. Conf. on high energy collisions. Oxford, April 5–7, 1972
2. Talman: Proc. of the Int. Conf. on Electron and Photon Interactions at High Energies. Bonn 1973
3. Berends, F.A.: Phys. Rev. D1, 2590 (1971)
4. Devenish, R.C.E., Lyth, D.H.: Phys. Rev. D5, 47 (1972)
5. Schmidt, W.: Preprint DESY 71/22