"Bidens eatonii". County-level distribution map from the North American Plant Atlas (NAPA). Biota of North America Program (BONAP). 2014.
ct.gov
"Connecticut's Endangered, Threatened and Special Concern Species 2015". State of Connecticut Department of Energy and Environmental Protection Bureau of Natural Resources. Retrieved 19 January 2018. (Note: This list is newer than the one used by plants.usda.gov and is more up-to-date.)