FOSTER STEVEN[A]. (2002). FIELD GUIDE TO WESTERN MEDICINAL PLANTS AND HERBS (2ND ED.). HOUGHTON MIFFIN COMPANY.
Chicago-viite (17. p.)FOSTER STEVEN[A]. FIELD GUIDE TO WESTERN MEDICINAL PLANTS AND HERBS. 2ND ED. BOSTAN: HOUGHTON MIFFIN COMPANY, 2002.
MLA-viite (9. p.)FOSTER STEVEN[A]. FIELD GUIDE TO WESTERN MEDICINAL PLANTS AND HERBS. 2ND ED. HOUGHTON MIFFIN COMPANY, 2002.
Varoitus: Nämä viitteet eivät aina ole täysin luotettavia.