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    H. V. Klapdor et al., Atomic Dasa aced Nuclear Data Tables, 31 (1984) 81.[2] A. Staudt et al., Same above, 44(1990) 87.[3] K. Takahashi et al., Same above, 12 (1973,) 101.[4] Zhao Jinhua et al., Chin, J, of Nucl. Physics, to be published.