الإتاحة: https://doi.org/10.1016/j.scib.2021.02.030Testhttp://hdl.handle.net/11577/3400491Test
الإتاحة: https://doi.org/10.1016/S0370-2693Test(03)00614-2http://hdl.handle.net/10281/153328Testhttp://www.sciencedirect.com/science/journal/03702693Test