Rozi, F., U. S. Pasaribu, U. Mukhaiyar, and D. Irianto. “The Modified Double Sampling Coefficient of Variation Control Chart ”. Journal of Mathematical and Fundamental Sciences, vol. 55, no. 1, Oct. 2023, pp. 56-76, doi:10.5614/j.math.fund.sci.2023.55.1.4.