Research Triangle Park, North Carolina : Air Quality Strategies and Standards Division, U.S. Environmental Protection Agency, Office of Air and Radiation, Office of Air Quality Planning and Standards, April 1996.
1996-
Ross-Winslow, Danielle J., author.
Fort Collins, Colorado : U.S. Department of the Interior, National Park Service, Natural Resource Program Center, 2010.
2010
Ross-Winslow, Danielle J., author.
Fort Collins, Colorado : U.S. Department of the Interior, National Park Service, Natural Resource Program Center, 2011.
2011