1. D. Sivers:Phys. Rev. D,3, 2275 (1971).
2. See, for instance,R. Oehme:Complex angular momentum, inStrong Interactions and High-Energy Physics, edited byR. G. Moorhouse (London, 1964).
3. M. Sugawara andA. Tubis:Phys. Rev.,130, 2127 (1963).
4. H. Fleming andT. Sawada:Lett. Nuovo Cimento,1, 1045 (1971).
5. E. C. Titchmarsh:The Theory of Functions, 2nd edition (Oxford, 1939).