1. Air Resource Specialists. (1999). EPAissues final regional haze regulations for protection of visibility in Class I areas. Interagency Monitoring of Protected Visual Environments (IMPROVE) Newsletter, 8(2), 2-5.
2. Effects of Sounds on Preferences for Outdoor Settings
3. Arrow, K. J., Solow, R., Portney, P. R., Learner, E. E., Radner, R.& Schuman, H. (1993). Report of the NOAA panel on contingent valuation. Federal Register, 58(10), 4602-4614.
4. Stress and the Environment
5. Impact of Impaired Visibility on Visitor Enjoyment of the Grand Canyon