For Echinacea
Baskin, J.M., K.M. Snyder, and C.C. Baskin. 1993. Nomenclatural history and taxonomic status of Echinacea angustifolia, E. pallida, and E. tennesseensis (Asteraceae). Sida 15: 597-604.
Binns, S.E., B.R. Baum, and J.T. Arnason. 2002. A taxonomic revision of Echinacea (Asteraceae: Heliantheae). Syst. Bot. 27: 610-632.
Cronquist, A. 1980. Asteraceae, Volume I, Vascular flora of the Southeastern United States. University of North Carolina Press, Chapel Hill, N.C.
Foster, S. 1991. Echinacea: nature's immune enhancer. Healing Arts Press, Rochester, VT. 150 pp.
Gaddy, L.L. 1991. The status of Echinacea laevigata (Boynton &Beadle) Blake. Asheville, NC: Unpublished report to the U.S. Fish and Wildlife Service. 24 pp.+ appendices and maps.
McGregor, R.L. 1968. The taxonomy of the genus Echinacea (Compositae). Univ. Kansas Sci. Bull. 48: 113-142.
McKeown, K. 1999. A review of the taxonomy of the genus Echinacea, in J. Janick (ed.). Perspectives on new crops and new uses. ASHS Press, Alexandria, VA. http://www.hort.purdue.edu/newcrop/proceedings1999/pdf/v4-482.pdf. Accessed 16 January 2021.
Urbatsch, L.E., K.M. Neubig, and P.B. Cox. 2006. Echinacea. In Flora of North America Editorial Committee. 2006c. Flora of North America north of Mexico. Volume 21, Magnoliophyta: Asteridae, part 6: Asteraceae, part 3. Oxford Univ. Press, New York, NY. 616 pp.
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