Natthida Thong-Iam และ Jutarat Vibulphol. (2009) Effects of situational variables on willingness to communicate and English classroom communication behaviors of ninth grade students. Chulalongkorn University:ม.ป.ท.Natthida Thong-Iam และ Jutarat Vibulphol. 2009. Effects of situational variables on willingness to communicate and English classroom communication behaviors of ninth grade students. ม.ป.ท.:Chulalongkorn University;Natthida Thong-Iam และ Jutarat Vibulphol. Effects of situational variables on willingness to communicate and English classroom communication behaviors of ninth grade students. ม.ป.ท.:Chulalongkorn University, 2009. Print.