Submitted on: 18 December 2014.
Revised on: 23 February 2015.
Accepted on: 17 April 2015.
___________________ASR Chiang Mai University Journal of Social Sciences and Humanities
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Submitted on: 01 May 2009.
Revised on: 13 July 2009.
Accepted on: 10 August 2009.
___________________ASR Chiang Mai University Journal of Social Sciences and Humanities
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