1. B. Richter, Nuclear Instr. and Meth. 136:47 (1976).
2. E. Keil et al., e+-e- colliders, in: Proc. of the second ICFA Workshop on Possibilities and Limitations of Accelerators and Detectors, U. Amaldi, ed., CERN, Geneva (1980).
3. B. Richter, in: Laser Acceleration of Particles, C. Joshi and T. Katsouleas, eds., American Institute of Physics, Conf. Proc, no. 130, p.8 (1985).
4. U. Amaldi, Nuclear Instr. and Meth. A 243: 312 (1986).
5. J. Lawson, Linear collider constraints: some implications for future accelerators, CERN report 85–15 (1985).