Kasum, A. S., A. K. Sanni, and T. O. Fagbemi. “Tax Revenue Generation by Nigerian States-An Empirical Study of Self-Assessment and Tax-Collection Contracting Systems in Kwara State”. Global Journal of Accounting, Vol. 5, no. 1, July 2019, pp. 27-36, http://ihafa.unilag.edu.ng/index.php/gja/article/view/458.