Effiong, S. A., and S. E. Attah. “Impact of Income Tax Rates on Tax Revenue in Nigeria: 1986 - 2015 in Focus”. International Journal of Economic Development Research and Investment (IJEDRI), vol. 7, no. 3, Dec. 2016, pp. 147-64, http://icidr.org.ng/index.php/Ijedri/article/view/914.