El malah, Mohammed, et al. “Integral Backstepping Based Nonlinear Control for Maximum Power Point Tracking and Unity Power Factor of a Grid Connected Hybrid Wind-Photovoltaic System”. Indonesian Journal of Electrical Engineering and Informatics (IJEEI), vol. 8, no. 4, Dec. 2020, pp. 706-22, https://doi.org/10.52549/ijeei.v8i4.2327.