Narumol Ruenwai. (1995) Study of discourse at the sentence level in research articles in the field of chemical engineering. Mahidol University,:ม.ป.ท.Narumol Ruenwai. 1995. Study of discourse at the sentence level in research articles in the field of chemical engineering. ม.ป.ท.:Mahidol University,;Narumol Ruenwai. Study of discourse at the sentence level in research articles in the field of chemical engineering. ม.ป.ท.:Mahidol University, 1995. Print.