Ongadi P M, Wahome R G, Wakhungu J W, Okitoi L O and Otieno K 2006: Bio-economic analysis of expenditure on inputs and output value from crops and grade dairy cattle sub systems in Vihiga, Kenya. Livestock Research for Rural Development.
Volume 18, Article #172. Retrieved , from http://www.lrrd.org/lrrd18/12/onga18172.htm