Affan Ahmed .J, et al. “Bivariate Optimal Replacement Policies Under Partial Product Process for Multistate Degenerative Systems With Varying Cost Structures”. Journal of Computational Analysis and Applications (JoCAAA), vol. 33, no. 07, Nov. 2024, pp. 1843-68, https://eudoxuspress.com/index.php/pub/article/view/2180.