«Genus: Zizia W. D. J. Koch». Germplasm Resources Information Network (GRIN). United States Department of Agriculture, Agricultural Research Service, Beltsville Area. Arxivat de l'original el 2011-06-05. [Consulta: 16 agost 2008].
«Genus: Zizia W. D. J. Koch». Germplasm Resources Information Network (GRIN). United States Department of Agriculture, Agricultural Research Service, Beltsville Area. Arxivat de l'original el 2011-06-05. [Consulta: 16 agost 2008].