Sjaifullah, Achmad. “Developing Speaking Materials for Students of Mechanical Engineering at State Polytechnic of Malang”. JLT: Jurnal Linguistik Terapan 1, no. 1 (May 31, 2011): 10–18. Accessed December 29, 2025. https://jurnal.polinema.ac.id/index.php/jlt/article/view/270.