Abdulghafour, A. B., Omran, S. H. . ., Ghulam, Z. J. and Rashed, M. K. (2017) “Quality Improvement of Petroleum Products Using Fuzzy Control Charts”, International Journal of Natural Sciences Research, 5(1), pp. 8–21. doi: 10.18488/journal.63.2017.51.8.21.