On ( s , S ) inventory system with random lead time and repeated demands. Ushakumari, P.V. — 2006 Journal of Applied Mathematics and Stochastic Analysis
A k -out-of- n reliability system with an unreliable server and phase type repairs and services: The ( N , T ) policy. Chakravarthy, Srinivas R.; Krishnamoorthy, A.; Ushakumari, P.V. — 2001 Journal of Applied Mathematics and Stochastic Analysis