References
Mrs.Supathida Nantaphum, teacher, Chiang Rai Rajabhat University, Chiang Rai, Tel. 0869147130, Email: tankokirei79@hotmail.com
Mr. Boonnuk Promdee, Senior Supervisor, Universal Travel Company, BKK, Tel. 081-343-3454, Email: Boonnuk@hotmail.com