1. W.H. Urbanus et al., in: T.I. Smith, H.A. Schwettman, R.L. Swent (Eds.), Proc. 16th Int. Conf. on Free Electron Lasers, Stanford, CA, USA, 1994, Nucl. Instr. and Meth. A 358 (1995) 155.
2. W.H. Urbanus et al., in: I. Ben-Zvi, S. Krinsky (Eds.), Proc. 17th Int. Conf. on Free Electron Lasers, New York, NY, USA, 1995, Nucl. Instr. and Meth. A 375 (1996) 401.
3. A.A. Varfolomeev et al., in: T.I. Smith, H.A. Schwettman, R.L. Swent (Eds.), Proc. 16th Int. Conf. on Free Electron Lasers, Stanford, CA, USA, 1994, Nucl. Instr. and Meth. A 358 (1995) 396.
4. G.G. Denisov et al., in: J.R. Birch, T.J. Parker (Eds.), Proc. 18th Int. Conf. on IR and MMWs, Colchester, United Kingdom, September 1993 p. 495.
5. C.A.J. van der Geer, M. Caplan, S.B. van der Geer, M.J. de Loos, A.G.A. Verhoeven, M.J. van der Wiel, W.H. Urbanus, these proceedings (19th Free Electron Laser Conf., Beijing, China, 1997) Nucl. Instr. and Meth. A 407 (1998) 70.