Wichaya Bovonwiwat และ Somsonge Burusphat. (2018) THE GRAMMATICAL DEVELOPMENT OF DIRECTIONAL VERBS IN BLACK TAI. <i>Humanities, Arts and Social Sciences Studies</i>, <i>18</i>(2), 399-427.Wichaya Bovonwiwat และ Somsonge Burusphat. "THE GRAMMATICAL DEVELOPMENT OF DIRECTIONAL VERBS IN BLACK TAI". Humanities, Arts and Social Sciences Studies 18 (2018):399-427.Wichaya Bovonwiwat และ Somsonge Burusphat. THE GRAMMATICAL DEVELOPMENT OF DIRECTIONAL VERBS IN BLACK TAI. Silpakorn University Research and Development Institute:ม.ป.ท. 2018.