Ismail, Hamid, and Saiful Saiful. “Upgrade the Students’ Speaking Ability: Implementation of the Callan Method at the Second Grade Students High School”. ETDC: Indonesian Journal of Research and Educational Review 3, no. 2 (March 27, 2024): 59–69. Accessed January 12, 2026. https://etdci.org/journal/ijrer/article/view/1386.