1. Lee, V. W. K. et al. in Recent Advances in Reproduction and Regulation of Fertility (ed. Talwar, G. P.) 241–252 (Elsevier, Amsterdam, 1979).
2. De Jong, F. H. Molec cell. Endocr. 13, 1–10 (1979).
3. Franchimont, P., Chari, S., Hazee-Hagelstein, M. T., Debruche, M. L. & Duraiswami, S. in The Testis in Normal and Infertile Men (eds Troen, P. & Nankin, H. R.) 253–270 (Raven, New York, 1977).
4. Keogh, E. J. et al. Endocrinology 98, 997–1004 (1976).
5. Baker, H. W. G. et al. Int. J. Andrology Suppl. 2, 115–125 (1978).