Kurniawan, Robi, Lia Resti Andani, and Sri Novita Yanda. “Is Group Investigation Technique Effective for Teaching Speaking in News Items? An Experimental Design at Senior High School”. Jurnal Pendidikan Tambusai 7, no. 1 (February 27, 2023): 2159–2169. Accessed July 12, 2025. https://jptam.org/index.php/jptam/article/view/5538.