Singtongratana, N. , Vadhanasin, S. and Singkhonrat, J. 2013. Hydroxychavicol and Eugenol Profiling of Betel Leaves from Piper betle L. Obtained by Liquid-Liquid Extraction and Supercritical Fluid Extraction. Agriculture and Natural Resources. 47, 4 (Aug. 2013), 614–623.