Lake George Association (New York).
DOI. NPS. Point Reyes National Seashore.
California Native Plant Society.
In Fremontia, the journal of the California Native Plant Society.
Missouri Department of Conservation.
See also: For more information about Invasive Tree Pests (insects and diseases) that are not native to Missouri
New York State Department of Health.
California Invasive Plant Council.
DOI. National Park Service.