Akpanibah, E.E., and P.A. Azor†. “Analysis of Investment Portfolio With 2 × 2 Positive Definite Matrix and Mortality Risk under Exponential Utility”. International Journal of Mathematical Analysis and Modelling 6, no. 2 (November 5, 2023). Accessed August 25, 2026. http://tnsmb.org/journal/index.php/ijmam/article/view/117.