Sitohang, Angelina -, and Masitowarni - Siregar. “IMPROVING STUDENTS™ SPEAKING ACHIEVEMENT IN AGREEMENT AND DISAGREEMENT EXPRESSIONS BY USING PROBLEM SOLVING STRATEGY AT GRADE VIII SMP SWASTA HKBP SIDORAME MEDAN”. TRANSFORM : Journal of English Language Teaching and Learning 3, no. 1 (March 15, 2014). Accessed August 26, 2025. https://jurnal.unimed.ac.id/2012/index.php/jelt/article/view/1819.