“Two-Unit System with Degradation and Degraded Failure”, J. Int. Acad. Phys. Sci., vol. 1, no. 3-4, pp. 171–182, Dec. 1997, Accessed: Oct. 23, 2026. [Online]. Available: http://www.iaps.org.in/journal/index.php/journaliaps/article/view/691