Higher plasma quercetin levels following oral administration of an onion skin extract compared with pure quercetin dihydrate in humans. - Zimmermann, Benno; Burak, Constanze; Brüll, Verena; Stehle, Peter; Egert, Sarah; Langguth, Peter; Stoffel-Wagner, Birgit; Sausen, Udo; Wolffram, Siegfried (European Journal of Nutrition, 2017)