Gardezi, S. A. R., H. U. Mughal, A. U. Rehman, A. Bari, and M. F. Zaman. “Effects of Crack Depth on the Mode Shapes and Natural Frequencies of Y-Junction Pipes”. The Nucleus, vol. 53, no. 1, Mar. 2016, pp. 70-77, http://www.thenucleuspak.org.pk/index.php/Nucleus/article/view/1162.