http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
NADP/NTN annual data summary, precipitation chemistry in the United States
Precipitation chemistry in the United States
Vols for 1983- : A contribution to the Task Group on DepositionMonotoring, Lead Agency, U.S. Geological Survey.
NADP annual data summary, precipitation chemistry in the United States