Jaca, C. A., M. R. Justiniane, and G. P. Gabatilla. “Duolingo Mobile Application As a Learning Tool in Improving the High School Students’ English Speaking Skill”. Randwick International of Education and Linguistics Science Journal, Vol. 7, no. 1, Mar. 2026, pp. 40-48, doi:10.47175/rielsj.v7i1.1157.