1. For reviews see, e.g., E. Reya, Phys. Rept. 69, 195 (1981)
2. A. H. Mueller, Lectures on perturbative QCD given at the Theoretical Advanced Study Institute, New Haven, 1985.
3. G. P. Lepage and S. J. Brodsky, Phys. Rev. D22, 2157 (1980)
4. G. P. Lepage, S. J. Brodsky, Tao Huang and P. B. Mackenzie, CLNS-82/522, published in the Proceedings of the Banff Summer Institute, 1981.
5. A. H. Mueller, Phys. Rept. 73, 237 (1981).