1. Britton, N. L. 1887. Columbia College Herbaria. Botanical Gazette 12: 9–11.
2. Jiménez-Mejías, P. 2017a. Boraginaceae, the Borage Family. In: R. F. C. Naczi, J. R. Abbott, and Collaborators. New Manual of Vascular Plants of Northeastern United States and Adjacent Canada, online edition. NYBG Press, Bronx, New York.
3. Jiménez-Mejías, P. 2017b. Verbenaceae, the Vervain Family. In: R. F. C. Naczi, J. R. Abbott, and Collaborators. New Manual of Vascular Plants of Northeastern United States and Adjacent Canada, online edition. NYBG Press, Bronx, New York.
4. Linnaeus, C. 1753. Species Plantarum, vol 1. Salvius, Stockholm.
5. Mackenzie, K. K. 1906. Onosmodium. Bulletin of the Torrey Botanical Club 32: 495–506.