Yousuf, A H, D. S. Al-Fattal, and B. A. Sadkhan. 2012. “Fatigue Behavior Safe Life Analysis of Composite Wind Turbine Blades Under Constant and Variable Spectrum Loading”. Nahrain University College of Engineering Journal 15 (1): 29-41. https://oldjournal.eng.nahrainuniv.edu.iq/index.php/main/article/view/636.