Jemmali, M., L. K. Bani Melhim, S. O. B. Alharbi, and A. S. Bajahzar. “Lower Bounds for Gas Turbines Aircraft Engines”. Communications in Mathematics and Applications, vol. 10, no. 3, Sept. 2019, pp. 637-42, doi:10.26713/cma.v10i3.1218.