E-Learning-Based Cloud Computing Environment: A Systematic Review, Challenges, and Opportunities. - Hana Eljak; Ashraf Osman Ibrahim; Fakhreldin Saeed; Ibrahim Abaker Targio Hashem; Abdelzahir Abdelmaboud; Hassan Jamil Syed; Anas Waleed Abulfaraj; Mohd Arfian Bin Ismail; Abubakar Elsafi (IEEE Access, 2024)