Abdul Ameer Mehdi, Hayder. “MATHEMATICAL FINITE ELEMENT MODEL FOR GENERAL ANALYSIS OF DOUBLE CURVED SHELL ACCORDING TO STRAIN BASED APPROACH”. Journal of Engineering and Sustainable Development, vol. 21, no. 6, Nov. 2017, pp. 20-38, https://jeasd.uomustansiriyah.edu.iq/index.php/jeasd/article/view/483.