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A. L. GAIDUK, V. M. GASAN, V. V. DEMIRSKII, S. V. ZHERLITSYN, I. G. KOLOBOV, E. D. TABACHNIKOVA, and FIV V. D, The role of the oxygen deficiency in the change of sound velocity in YBa2Cu3O7-d below 20 K, Low Temp. Phys. 16, (1990) [Fiz. Nizk. Temp. 16, 606-606, (1990)].