S. Yacob, M. Amran Md Ali, Q. Ahsan, N. Arifin, and R. Ali, “A brief review of grey fuzzy logic technique research progression from 2010 to 2016”, IJET, vol. 7, no. 2.29, pp. 41–42, May 2018, doi: 10.14419/ijet.v7i2.29.13125.