Inverse theorems of approximation by biharmonic functions
English version (Springer): Ukrainian Mathematical Journal 38 (1986), no. 5, pp 484-489.
Citation Example: Gorbachuk V. I., Timoshchuk V. N. Inverse theorems of approximation by biharmonic functions // Ukr. Mat. Zh. - 1986. - 38, № 5. - pp. 569–575.
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