Lipscomb, Barney. “Monarchs and Milkweed: A Migrating Butterfly, A Poisonous Plant, and Their Remarkable Story of Coevolution”. Journal of the Botanical Research Institute of Texas 11, no. 1 (July 24, 2017): 80. Accessed December 1, 2022. https://journals.brit.org/jbrit/article/view/1184.