Phạm, H. P. Y. (2017). An investigation into EFL learners' perceptions and practices of politeness strategies in the speech ACT of requesting at a foreign language center in Can Tho city: Master of education. Program: Principles and methods in English language education. Cần Thơ: Trường Đại học Cần Thơ.

Phạm, Hoàng Phi Yến. An Investigation Into EFL Learners' Perceptions and Practices of Politeness Strategies in the Speech ACT of Requesting At a Foreign Language Center in Can Tho City: Master of Education. Program: Principles and Methods in English Language Education. Cần Thơ: Trường Đại học Cần Thơ, 2017.

Phạm, Hoàng Phi Yến. An Investigation Into EFL Learners' Perceptions and Practices of Politeness Strategies in the Speech ACT of Requesting At a Foreign Language Center in Can Tho City: Master of Education. Program: Principles and Methods in English Language Education. Cần Thơ: Trường Đại học Cần Thơ, 2017.