Quantification of xanthohumol, isoxanthohumol, 8-prenylnaringenin, and 6-prenylnaringenin in hop extracts and derived capsules using secondary standards - Dhooghe, L; Naessens, T; Heyerick, A; De Keukeleire, D; Vlietinck, A; Pieters, L; Apers, S (Planta Medica, 2010)