Hussain, Haydar A., et al. “Stress Analysis of Fiber-Reinforced Composite Built-up Beam Using the Unit Cell Method”. Nahrain University College of Engineering Journal, vol. 11, no. 3, Mar. 2008, pp. 419-28, https://oldjournal.eng.nahrainuniv.edu.iq/index.php/main/article/view/537.