13Negewo, Takele, Abreham Feyissa, Minale Liben, and Beyeneshe Zemichael. "Barley Research and Development in Ethiopia."(2011) Achievements of Research on Weeds and Their Management in Barley in Ethiopia.
14Nyssen, Jan, Katrien Descheemaeker, Amanuel Zenebe, Jean Poesen, Jozef Deckers, and Mitiku Haile. "Transhumance in the Tigray Highlands (Ethiopia)."Mountain Research and Development 29, no. 3 (2009): 255-264.