Shakeel, M., K. Rahman, M. A. Khan, and M. Ullah. “Induced Averaging Aggregation Operators With Interval Pythagorean Trapezoidal Fuzzy Numbers and Their Application to Group Decision Making”. The Nucleus, vol. 54, no. 2, June 2017, pp. 140-53, http://www.thenucleuspak.org.pk/index.php/Nucleus/article/view/112.