T. T. Nguyen, “A Contrastive Study of Theme Types in Academic IELTS Essays Written by English-Majored Students and IELTS Candidates”, J. Knowl. Learn. Sci. Technol., vol. 3, no. 2, pp. 30–42, Jun. 2024, doi: 10.60087/jklst.vol3.n2.p42.