Oukaili, Nazar, and Hassan Yasseen. “Theoretical Investigations on the Structural Behavior of Biaxial Hollow Concrete Slabs”. Journal of Engineering 21, no. 6 (June 1, 2015): 108-130. Accessed November 29, 2019. http://joe.uobaghdad.edu.iq/index.php/main/article/view/417.