Tuangporn Somsamai. 1992. Readability of college textbooks as basis for the threshold level of Thai engineering freshmen. Department of Language Teaching, University of Philippines System Deliman;
Tuangporn Somsamai. (1992) Readability of college textbooks as basis for the threshold level of Thai engineering freshmen . University of Philippines System Deliman/Quezon.
Tuangporn Somsamai. Readability of college textbooks as basis for the threshold level of Thai engineering freshmen. . Quezon:University of Philippines System Deliman, 1992.
Tuangporn Somsamai. (1992) Readability of college textbooks as basis for the threshold level of Thai engineering freshmen . University of Philippines System Deliman/Quezon.