Quyền, P., Đỗ Hân, N. Hậu, and L. Trí. “Preparation of Cough Syrup Containing Dextromethorphan HBr, Promethazine HCl and Preliminary Assessment of Formulation Stability”. Science and Technology Development Journal: Health Sciences, Vol. 2, no. 2, Aug. 2021, pp. 214-21, doi:https://doi.org/10.32508/stdjhs.v2i2.474.