1. Hughes, F., Year Book, Khedivial Agric. Soc. ( 1909).
2. Prescott, J. A., Bull. No. 13 Sultanic Agric. Soc. ( 1924).
3. Khalil, F., Gracie, D. S., and Enan, Ministry of Agric., Egypt, Chemical and Agric. Sec., 152, 1 ( 1935).
4. Mahmoud, A., and Crowther, F., Royal Agric. Soc., Egypt, Tech. Bull. 22 ( 1935).
5. Mahmoud, A., and Crowther, F., Royal Agric. Soc., Egypt, Tech. Bull. 26 ( 1936).