1. Ae, N., Arihara, J. and Okada, K. 1991. In: Phosphorus Nutrition of Grain Legumes in the SemiArid Tropics, pp. 33–41 (eds. C. Johansen, K. K. Lee and K. L. Sahrawat). Patancheru, Andhra Pradesh, India:, ICRISAT.
2. Agarwala, S. C. and Sharma, C. P. 1979. Recognizing Micronutrient Disorders of Crop Plants on the Basis of Visible Symptoms and Plant Analysis. Lucknow, U. P., India:, Department of Botany, Lucknow University.
3. Ange’lica Sadzwaka, R. 1987. Agricultura Técnica (Chile) 47: 350–354.
4. Ayers, A. D. and Eberhard, D. L. 1960. Agronomy Journal 52: 110–111.
5. Ayoub, A. 1970/71. In: Annual Report of the Hudeiba Research Station, pp. 60–80. Democratic Republic of the Sudan:, Agricultural Research Corporation, Ministry of Agriculture.