Asymmetric Effects of COVID-19 Deaths and Oil Price Shocks on Stock Market Returns in Some Selected African Countries: Evidence From Nonlinear ARDL Approach. iref [Internet]. 2026 Feb. 11 [cited 2026 Mar. 7];8(1):p1. Available from: https://journal.chapjulypress.org/index.php/iref/article/view/2714