Rafindadi, A. A., and Z. A. Olanrewaju. “Internal Control System, Sustainable Management and Service Delivery of NGO’s in Nigeria: An Empirical Analysis”. International Review of Management and Marketing, vol. 9, no. 2, Mar. 2019, pp. 89-103, https://econjournals.com/index.php/irmm/article/view/7773.