Papadopoulos, George; Boskou, Dimitrios (1991). “Antioxidant effect of natural phenols on olive oil”. Journal of the American Oil Chemists' Society68 (9): 669. doi:10.1007/BF02662292.
Determination of free and bound phenolic acids in beer. M. Nardini and A. Ghiselli, Food Chemistry, January 2004, Volume 84, Issue 1, Pages 137–143, doi:10.1016/S0308-8146(03)00257-7