Memory Effects of Standardized Extracts of Panax ginseng (G115), Ginkgo biloba (GK 501) and their Combination Gincosan® (PHL-00701) - Petkov, Vesselin D; Kehayov, Rumen; Belcheva, Stiljana; Konstantinova, Elena; Petkov, Vesselin V; Getova, Damjanka; Markovska, Victoria (Planta Medica, 1993)