1. Cates, W., Farley, T.M.M., and Rowe, P.J. (1985) World Wide Patterns of Infertility: Is Africa Different, Lancet 1, 596–598.
2. Baker, H.G.W., Gurger, H.G., de Kretser, D.M., and Hudson, B. (1986) Relative Incidence of Etiologic Disorders in Male Infertility, in Male Reproductive Dysfunction (Sauten, R.S. and Swerdloff, R.S., eds.) pp. 341–372 Marcel Dekker, New York.
3. Cai, X., and Marik, J.J. (1989) Improving Penetrating Capacity of Spermatozoa with Poor Motility by Addition of Caffeine at Coincubation with Zona Free Hamster Ova, Fertil. Steril. 51, 719–721.
4. Nissen, H.P., and Kreysel, H.W. (1983) Polyunsaturated Fatty Acids in Relation to Sperm Motility, Andrologia 15, 264–269.
5. Gulaya, N.M., Tronko, M.D., Volkov, G.L., and Margitich, M. (1993) Lipid Composition and Fertile Ability of Human Ejaculate, Ukr. J. Biochem. 65, 64–70.