C. Peechapol, J. Na-Songkhla, S. Sujiva, and A. Luangsodsai, “Development of Smartphone Application Based on the Theory of Planned Behaviour to Enhance Self-Efficacy for Online Learning”, Int. J. Interact. Mob. Technol., vol. 12, no. 4, pp. pp. 135–151, Aug. 2018.