El-Shahed, Moustafa, and Reem Alharbi. “Optimal Control Strategies for Dual-Strain Hepatitis B Dynamics: A Mathematical and Cost-Effectiveness Study”. Contemporary Mathematics 6, no. 5 (August 29, 2025): 5652–5690. Accessed December 15, 2025. https://ojs.wiserpub.com/index.php/CM/article/view/7666.