This definition appears rarely
Said, Aarat Wendem Ageneh and J. A. Kategile Eds. ). Proceedings of the First Joint workshop held in Lilongwe, Malawi, by the Pasture Network for eastern and Southern Africa (PANESA) and African Research Network for Agricultural by-products (ARNAB). International Livestock Centre for Africa (ILCA). 5-9 December, 1988. pp. 114-125.