1. Anapa PL, Mariki WL (1999) Effects of crop rotation, tillage method and N application on wheat yield at Hanang wheat farms, Tanzania. In: Proc10th Reg wheat workshop for E, S, C Africa. CIMMYT. U. of Stellenbosch RSA, 14–18 Sep 1998. Addis Ababa, Ethiopia, pp 347–351
2. CIMMYT (1988) From agronomic data to farmer recommendations: an economics training manual. CIMMYT, Mexico DF
3. Danagro (1995) A progress report, unpubl
4. Erkossa T, Mamo T, Kidane S, Abebe M (2000) Response of some durum wheat landraces to nitrogen application on Ethiopian vertisols. 11th Reg Wheat Workshop E C S Africa. CIMMYT Sep 2000. Addis AbabaEthiopia, pp 229–238
5. Gashawbeza B, Yaekob A, Zemede A, Kifetew J, Tadesse T, Mekuria B (2003) Fertilizer N effects on yield and grain quality of durum wheat. Trop Agr 80:146–151