Mccoy, J.H., Widrlechner, M.P., Carstens, J.D. 2006. A comprehensive Echinacea germplasm collection located at the North Central Regional Plant Introduction Station, Ames, Iowa. International Plant Propagators Society Proceedings. 55:439-440.
Mccoy, J.H., Widrlechner, M.P., Carstens, J.D. 2005. A comprehensive echinacea germplasm collection located at the North Central Regional Plant Introduction Station, Ames, Ia. Symposium Proceedings. p. 5.
McCoy, J.H., Widrlechner, M.P., Carstens, J.D. 2005. A comprehensive Echinacea germplasm collection located at the North Central Regional Plant Introduction Station, Ames, Iowa. HortScience. 40:1063.