Rahadianto, Irfan Dwi, et al. “Analisis Merrill’s First Principles of Instruction Pada Game Edukasi Covid Fighter Dengan Pendekatan Formal Element”. Jurnal Penelitian Pendidikan, vol. 22, no. 1, Apr. 2022, pp. 28-41, https://doi.org/10.17509/jpp.v22i1.45691.