1. NPS organic act, 16 USC 1.
2. Public Law No. 100-91, 16 U.S.C. 1a-1 note, 1992.
3. NPS, Report on effects of aircraft overflights on the National Park System, Report to Congress, US Department of the Interior/National Park Service, July 1995.
4. Hearing in vertebrates: a psychophysics databook;Fay,1998
5. Public Law 106-181, 49 USC 40128.