Piyasuang Kulmala. 2004. A survey of teaching pragmatic language use in EFL classrooms in upper secondary schools in Kamphaengphet province. Field of Study English, Naresuan University;
Piyasuang Kulmala. (2004) A survey of teaching pragmatic language use in EFL classrooms in upper secondary schools in Kamphaengphet province . Naresuan University/Phitsanulok.
Piyasuang Kulmala. A survey of teaching pragmatic language use in EFL classrooms in upper secondary schools in Kamphaengphet province. . Phitsanulok:Naresuan University, 2004.
Piyasuang Kulmala. (2004) A survey of teaching pragmatic language use in EFL classrooms in upper secondary schools in Kamphaengphet province . Naresuan University/Phitsanulok.