Bach, Pham Cao, et al. “Quantitative Analysis of Caffeine in the Leaves and Flowers of Camellia Chrysantha by High-Performance Liquid Chromatography With DAD Detection”. Vietnam Journal of Science and Technology, vol. 58, no. 3, May 2020, pp. 267-73, doi:10.15625/2525-2518/58/3/14366.