1. Hooker, W. J. 1857. Curtis’s botanical magazine, series 3,13: t. 4966 and text.
2. Jones, Jr. S. B. 1968. Chromosome numbers in southeastern United States Compositae, I. Torrey Bot. Club Bull.95: 393–395.
3. L’Heritier de Brutelle, C. L. 1788. Sertum anglicum, facsimile with critical studies and a translation, edition.1963. Pittsburgh: Hunt Botanical Library.
4. Radford, A. E., H. E. Ahles, and C. R. Bell. 1968. Manual of the vascular flora of the Carolinas. Chapel Hill: University of North Carolina Press.