Temirov, M. “Improving Intelligibility of Voiced and Voiceless ‘th’ Consonants in the Speeches of Sophomores Using Pronunciation Drills”. JLT: Jurnal Linguistik Terapan, vol. 4, no. 1, May 2014, pp. 27-49, https://jurnal.polinema.ac.id/index.php/jlt/article/view/279.