“Using Markov Chains to Establish the System of Reliability and Preventive Maintenance With Application Part”. 2021. Journal of Al-Rafidain University College For Sciences ( Print ISSN: 1681-6870 ,Online ISSN: 2790-2293 ) 46 (1): 535-44. https://doi.org/10.55562/jrucs.v46i1.104.