1. Description of the Ecoregions of the United States;Bailey;U.S. Department of Agriculture, Miscellaneous Publication No. 1391,1980
2. National Atmospheric Deposition Program, NADP Instruction Manual Site Operation;Bigelow,1982
3. A field evaluation of the Hasl wet-dry deposition collector
4. Practical Nonparametric Statistics;Conover,1980
5. Specifications for Purchase of Precipitation Sampler, letter to National Atmospheric Deposition Program participants;Cowling,1978