Anyanwu, John C, and Joanna C Anyanwu. “Accounting for the Rising Value Added in Services Compared to That in Agriculture in African Economies”. Asian Journal of Economic Modelling 6, no. 4 (October 25, 2018): 476–500. Accessed May 14, 2026. https://archive.aessweb.com/index.php/5009/article/view/334.