“DB - Optimal Criterion Design to Estimate the Parameters of Some Proportional Hazards Model with Minimal Variance with Practical Application” (2022) Journal of Al-Rafidain University College For Sciences ( Print ISSN: 1681-6870 ,Online ISSN: 2790-2293 ), 50(3), pp. 87–94. doi:10.55562/jrucs.v50i3.503.