Huong Ngoc Thi Dao, The Thai Nguyen, Tran Huyen Thi Nguyen, Thuy Hong Ngoc Phan and Phuong Hoang Tran 2024. Preparation of pyridinium-based ionic liquid and application as a green catalyst for the synthetic route of 4H-1-benzopyran-5(6H)-ones. Vietnam Journal of Science, Technology and Engineering. 66, 1 (Mar. 2024), 34-45. DOI:https://doi.org/10.31276/VJSTE.66(1).34-45.