Efendi, S.; Sriyanah, N.; Fatmawati, F.; Livana, P. H.; Suswani, A.; Nuratifah, N. Duration of Smartphone Usage in Online Learning During the COVID-19 Pandemic and the Occurrence of Computer Vision Syndrome in the Students of MTsN 1 Bone. Int. J. of Health Sci. 2022, 6, 7652-7659.