A. Vinca, “Assessing Instrument Reliability and Validity in Exploring Teacher’s Roles and Attitude in ESP”, IJSBAR, vol. 36, no. 2, pp. 71–80, Sep. 2017, Accessed: Sep. 18, 2025. [Online]. Available: https://www.gssrr.org/JournalOfBasicAndApplied/article/view/8170