Cossio-Bolaños, M. A., C. L. Andruske, R. Vargas-Vitoria, J. Lagos-Luciano, C. Luarte-Rocha, J. Sulla-Torres, and R. Gomez-Campos. “Validation of an Instrument to Assess the Skill Levels of Adolescent Students to Learn Knowledge: Skill Levels to Learn Knowledge”. International Electronic Journal of Elementary Education, vol. 12, no. 1, Oct. 2019, pp. 47-52, https://iejee.com/index.php/IEJEE/article/view/825.