Y. Waruwu, “Enhancing Formal Academic Speaking through Problem-Based Learning in EFL Higher Education”, J. Engl. Lang. Teach. Fak. Pendidik. Bhs. Seni Program Studi Pendidik. Bhs. Ingg. IKIP Mataram, vol. 13, no. 1, pp. 153–165, Jun. 2026.