1. Dictionary of Natural Products, 1999. CD-ROM Version 8:1, Chapman & Hall, Boca Raton, FL
2. Lignans of Forsythia intermedia
3. USDA-ARS-GRIN database, 1999. National Germplasm Resources Laboratory, Beltsville, MD, USA, available on-line at: www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?12658