Sexual enhancement products for sale online: raising awareness of the psychoactive effects of yohimbine, maca, horny goat weed, and Ginkgo biloba - Corazza, O; Martinotti, G; Santacroce, R; Chillemi, E; Giannantonio, M D; Schifano, F; Cellek, S (Biomed Res Int, 2014)