D. M. Dalilis, F. T. M. Kiw-an, G. E. Siadto, J. R. O. Pelila, and S. M. G. Bangkiko, “Exploring Affective Filter Levels in Spanish as a Foreign Language Course Among Tertiary Students”, IJRER, vol. 4, no. 3, pp. 874–887, Jun. 2025.