ឯកសារយោង
1) Creswell, J. W., & Creswell, J. D. (2018). Research design: Qualitative, quantitative, and mixed methods approaches (5th ed.). SAGE Publications.
2) Fraenkel, J. R., Wallen, N. E., & Hyun, H. H. (2019). How to design and evaluate research in education (10th ed.). McGraw-Hill Education.
3) Kumar, R. (2019). Research methodology: A step-by-step guide for beginners (5th ed.). SAGE Publications.