Gyamfi, E. N., and K. A. Kyei. “Modeling Stock Market Returns under Self-Exciting Threshold Autoregressive Model: Evidence from West Africa”. International Journal of Economics and Financial Issues, vol. 6, no. 3, July 2016, pp. 1194-9, https://www.econjournals.com/index.php/ijefi/article/view/2418.