Antokhin, Yu. T. Certain problems in Hilbert space and stable methods for solving them. (English) Zbl 0232.47022 Differ. Equations 3 (1967), 594-606 (1971). MSC: 47A50 47A10 47A75 PDFBibTeX XMLCite \textit{Yu. T. Antokhin}, Differ. Equations 3, 594--606 (1971; Zbl 0232.47022)
Liskovets, O. A. Incorrect problems with a closed irreversible operator. (English) Zbl 0215.48703 Differ. Equations 3(1967), 324-329 (1971). MSC: 47A05 47B07 47A50 47J05 PDFBibTeX XMLCite \textit{O. A. Liskovets}, Differ. Equations 3, 324--329 (1971; Zbl 0215.48703)