Duke's Phytochemical and Ethnobotanical Database
http://www.ars-grin.gov/duke/

Medline
www4.ncbi.nlm.nih.gov/PubMed/

Molecular Expressions: Phytochemical Gallery - Butyl Phthalide
http://micro.magnet.fsu.edu/phytochemicals/pages/butylphthalide.html

Relay Synthesis of natural diligustilide dimers
http://osuno.fciencias.unam.mx/~yrios/ftal2/