P. N. Amaliarrafiun, Hastini, M. Maf’ulah, and Zarkiani, “Investigating EFL Students’ Difficulties in Producing English Interdental Fricatives (/Θ/ and /Ð/): A Descriptive Quantitative Study”, Fost.j.e.l.t., vol. 7, no. 2, pp. 547-561, Apr. 2026.