1. Forest Health: Its Assessment and Status;Innes,1993
2. Ozone injury to the foliage of Pinus ponderosa;Miller;Phytopathology,1963
3. Field surveys;Skelly,1979
4. Diagnosing Injury to Eastern Forest Trees;Skelly,1988
5. A closer look at forest decline: A need for more accurate diagnostics;Skelly,1992