1. Leydig F. Zur anatomie der mannlichen geschlechtsorgane and analdrusen der saugethiere. Z Wissenschaftliche Zool 1850;2:1–57.
2. Christensen AK, Gillim S. The correlation of fine structure and function in steroid-secreting cells, with emphasis on those of the gonads. In: McKerns K, ed. The Gonads., AppletonCentury-Crofts, New York, 1969:415–487.
3. Christensen AK. Leydig cells. In: Handbook of Physiology, vol. 5, American Physiology Society, 1975:57–94.
4. Schulze C. Sertoli Cells and Leydig Cells in Man. SpringerVerlag, Berlin, 1984;88:1–104.
5. De Kretser DM, Kerr JB. The cytology of the testis. In: Knobil E, Neill JD, eds. The Physiology of Reproduction, Raven Press, New York, 1994;1170–1290.