Amethystea caerulea
- Photograph, systematic position, morphology, biology, distribution, ecology and economic significance of the blue amethystea.
- http://www.agroatlas.spb.ru/weeds/Amethystea_caerulea_en.htm

Amethystea
- A systematic description of the physical characteristics of Amethystea, the genera and Amethystea, the species.
- http://flora.huh.harvard.edu/china/PDF/PDF17/amethystea.pdf