"Genus: Oenothera L". Germplasm Resources Information Network. United States Department of Agriculture. 2004-03-22. Archived from the original on 14 September 2010. Retrieved 2010-10-28.
"Genus: Oenothera L". Germplasm Resources Information Network. United States Department of Agriculture. 2004-03-22. Archived from the original on 14 September 2010. Retrieved 2010-10-28.