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Nunthaporn Promrat. (1998) A study of English vocabulary competency and problems of the tourist police in the lower central region of Thailand . Naresuan University/Phitsanulok.
Nunthaporn Promrat. A study of English vocabulary competency and problems of the tourist police in the lower central region of Thailand. . Phitsanulok:Naresuan University, 1998.
Nunthaporn Promrat. (1998) A study of English vocabulary competency and problems of the tourist police in the lower central region of Thailand . Naresuan University/Phitsanulok.