1. World Health Organization: Laboratory manual for the examination of human semen and semen-cervical mucus interaction. Cambridge University Press, Cambridge 1987.
2. World Health Organization, prepared by F.H. Comhaire, D. deKretser, T.M.M. Farley and P.J. Rowe: Towards more objectivity in diagnosis and management of male infertility.Int J Androl.1987, supplement 7.