1. Akoroda, M. O., J. E. Wilson & H. R. Chheda, 1981. Artificial pollination, pollen viability, and storage in white yam. Tropical root crops: Research strategies for the 1980s. IDRC-163e, Ottawa, Canada, pp. 189–194.
2. Brewbaker, J. L. & B. H.Kwack, 1963. The essential role of calcium ion in pollen germination and pollen tube growth. Amer. J. Bot. 50: 859–865.
3. Burkill, I. H., 1960. The organography and evolution of Dioscoreaceae, the family of yams. J. Linn. Soc. (Bot.) 56: 316–412.
4. Chinwuba, P. M., 1971. Review of yam production in Nigeria during the last ten years (1961–1971). Fed. Dept. Agric. Res., Umuahia-Ibeku, Nigeria. pp. 6.
5. Coursey, D. G., 1967. Yams. Longmans, London. pp. 230.