1. ZEUS Collaboration, ZEUS 1995 preliminary data, Abstract 770, Proceedings of the XXIX ICHEP'98 Conference, Vancouver, Canada, 1998; A.T. Doyle, hep-ex/9808022; J. Breitweg et al., hep-ex/9809005, to appear in the European J. Phys. C.
2. H1 Collaboration, H1 1995 preliminary data; see A. Caldwell, invited talk at the DESY theory workshop, October 1997 and DIS98, Brussels, April 1998; A.D. Martin, R.G. Roberts, W.J. Stirling, R.S. Thorne, talk presented at DIS98, Brussels, April 1998, hep-ph/9805205.
3. See, for example, A.D. Martin, R.G. Roberts, W.J. Stirling, Phys. Lett. B 387 (1996) 419; and [11]below.
4. GRV (1998), M. Glück, E. Reya, A. Vogt, Eur. Phys. J. C 5 (1998) 461.
5. MRS (1998), A.D. Martin, R.G. Roberts, W.J. Stirling, Eur. Phys. J. C 4 (1998) 463.