Z. Mekonnen, A. Worku, T. Yohannes, T. Bahru, T. Mebratu, and D. Teketay, “Economic Contribution of Gum and Resin Resources to Household Livelihoods in Selected Regions and the National Economy of Ethiopia”, Ethnobot. Res. App., vol. 11, pp. 273–288, Dec. 2013.