Cotsworth, E. 2004a. Letter to R.P. Detwiler (1 Enclosure). 20 May 2004. ERMS 535554. U.S. Environmental Protection Agency, Office of Air and Radiation, Washington, DC.
Cotsworth, E. 2005. Letter to I. Triay (1 Enclosure). 4 March 2005. ERMS 538858. U.S. Environmental Protection Agency, Office of Air and Radiation, Washington, DC.