Unidentified Excess Alpha-Activity in the 4.4-Mev Region in Natural Thorium Samples

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CHERRY, R., RICHARDSON, K. & ADAMS, J. Unidentified Excess Alpha-Activity in the 4.4-Mev Region in Natural Thorium Samples. Nature 202, 639–641 (1964) doi:10.1038/202639a0

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