Prastiyono, Hendri, et al. “Development of E-Learning, Mobile Apps, Character Building, and Outdoor Study (EMCO Learning Model) to Improve Geography Outcomes in the 21st Century”. International Journal of Interactive Mobile Technologies (iJIM), vol. 15, no. 07, Apr. 2021, pp. pp. 107-122, doi:10.3991/ijim.v15i07.21553.