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	title = {A global assessment of natural sources of atmospheric trace metals},
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	year = {1989},
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	author = {Nriagu, J.O.}
}
@article {68,
	title = {Quantitative Assessment of Worldwide Contamination of Air, Water, and Soils by Trace Metals},
	journal = {Nature},
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	year = {1988},
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	author = {Nriagu, J.O. and Pacyna, J.F.}
}
