Yakubovich, Dmitry Vector semi-Fredholm Toeplitz operators and mean winding numbers. (English) Zbl 1172.47023 Nagoya Math. J. 195, 57-75 (2009). MSC: 47B35 47A53 47G30 46E15 55M25 93B05 PDFBibTeX XMLCite \textit{D. Yakubovich}, Nagoya Math. J. 195, 57--75 (2009; Zbl 1172.47023) Full Text: DOI arXiv Euclid
Ball, Joseph A. Operator extremal problems, expectation operators and applications to operators on multiply connected domains. (English) Zbl 0432.47013 J. Oper. Theory 1, 153-175 (1979). MSC: 47B20 55Q25 47A45 30D55 46J15 PDFBibTeX XMLCite \textit{J. A. Ball}, J. Oper. Theory 1, 153--175 (1979; Zbl 0432.47013)