Bui Thanh Hoa, Tran Thi Lan Anh, and Nguyen Trung Kien. “A Study of Negation-Indicated Words in Vietnamese”. Journal of English Teaching as a Foreign Language 6, no. 3 (December 22, 2020): 48-52. Accessed July 22, 2024. https://ejournal.uhn.ac.id/index.php/jetafl/article/view/96.