In vitro and in vivo immune stimulating effects of a new standardized Echinacea angustifolia root extract (Polinacea™) - Morazzoni, P; Cristoni, A; Di Pierro, F; Avanzini, C; Ravarino, D; Stornello, S L; Zucca, M; Musso, T (Fitoterapia, 2005)