1. A Donnachie and P V Landshoff, Phys. Lett. B296, 227 (1992)
2. F E Low, Phys. Rev. D12, 163 (1975)
3. S Nussinov, Phys. Rev. D14, 246 (1976)
4. E A Kuraev, L N Lipatov and V S Fadin, Sov. Phys. JETP 45, 199 (1977)
5. Ya Ya Balitsky and L N Lipatov, Sov. J. Nucl. Phys. 28, 22 (1978)