Chanit Tjinto. 1999. study of English communication problems between the United Airlines' customer service representatives and its customers at Don Muang Airport. Bangkok:Ramkhamhaeng University;
Chanit Tjinto. (1999) study of English communication problems between the United Airlines' customer service representatives and its customers at Don Muang Airport (รายงานผลงานวิจัย). Ramkhamhaeng University:Bangkok.
Chanit Tjinto. study of English communication problems between the United Airlines' customer service representatives and its customers at Don Muang Airport. Bangkok:Ramkhamhaeng University, 1999.