Hening, Alexandru; Kolb, Martin Quasistationary distributions for one-dimensional diffusions with singular boundary points. (English) Zbl 1435.60055 Stochastic Processes Appl. 129, No. 5, 1659-1696 (2019). Reviewer: Isamu Dôku (Saitama) MSC: 60J60 58J65 58J05 35J10 35P05 47F05 PDF BibTeX XML Cite \textit{A. Hening} and \textit{M. Kolb}, Stochastic Processes Appl. 129, No. 5, 1659--1696 (2019; Zbl 1435.60055) Full Text: DOI arXiv OpenURL
Winkler, Henrik Two-dimensional Hamiltonian systems. (English) Zbl 1337.47113 Alpay, Daniel (ed.), Operator theory. With 51 figures and 2 tables. In 2 volumes. Basel: Springer (ISBN 978-3-0348-0666-4/print; 978-3-0348-0667-1/ebook; 978-3-0348-0668-8/print+ebook; 978-3-0348-0692-3/online (updated continuously)). Springer Reference, 525-547 (2015). Reviewer: Bilender P. Allahverdiev (Isparta) MSC: 47N20 34B20 47E05 34L40 34B09 47-02 PDF BibTeX XML Cite \textit{H. Winkler}, in: Operator theory. With 51 figures and 2 tables. In 2 volumes. Basel: Springer. 525--547 (2015; Zbl 1337.47113) Full Text: DOI Link OpenURL
Weber, Michel J. G. On small deviations of stationary Gaussian processes and related analytic inequalities. (English) Zbl 1319.60073 Sankhyā, Ser. A 75, No. 2, 139-170 (2013). MSC: 60G15 60G10 60F99 60F10 60F15 11C20 15B05 15A42 PDF BibTeX XML Cite \textit{M. J. G. Weber}, Sankhyā, Ser. A 75, No. 2, 139--170 (2013; Zbl 1319.60073) Full Text: DOI arXiv OpenURL
Böttcher, Albrecht; Pietsch, Albrecht Orthogonal and skew-symmetric operators in real Hilbert space. (English) Zbl 1277.47022 Integral Equations Oper. Theory 74, No. 4, 497-511 (2012). Reviewer: Jamilson Ramos Campos (João Pessoa) MSC: 47A65 47B06 47B10 PDF BibTeX XML Cite \textit{A. Böttcher} and \textit{A. Pietsch}, Integral Equations Oper. Theory 74, No. 4, 497--511 (2012; Zbl 1277.47022) Full Text: DOI OpenURL
Fleige, Andreas A failing eigenfunction expansion associated with an indefinite Sturm-Liouville problem. (English) Zbl 1248.34131 J. Math. Anal. Appl. 389, No. 2, 932-949 (2012). Reviewer: Petru A. Cojuhari (Kraków) MSC: 34L10 34B24 PDF BibTeX XML Cite \textit{A. Fleige}, J. Math. Anal. Appl. 389, No. 2, 932--949 (2012; Zbl 1248.34131) Full Text: DOI OpenURL
Behrndt, Jussi; Trunk, Carsten Sturm–Liouville operators with indefinite weight functions and eigenvalue depending boundary conditions. (English) Zbl 1099.34018 J. Differ. Equations 222, No. 2, 297-324 (2006). Reviewer: Pavel Rehak (Brno) MSC: 34B09 34B20 47B50 47E05 PDF BibTeX XML Cite \textit{J. Behrndt} and \textit{C. Trunk}, J. Differ. Equations 222, No. 2, 297--324 (2006; Zbl 1099.34018) Full Text: DOI OpenURL
Galántai, A. On the rate of convergence of the alternating projection method in finite dimensional spaces. (English) Zbl 1074.65059 J. Math. Anal. Appl. 310, No. 1, 30-44 (2005). MSC: 65J10 65Fxx 41A25 PDF BibTeX XML Cite \textit{A. Galántai}, J. Math. Anal. Appl. 310, No. 1, 30--44 (2005; Zbl 1074.65059) Full Text: DOI OpenURL
Bauer, Robert O. Chordal Loewner families and univalent Cauchy transforms. (English) Zbl 1067.30035 J. Math. Anal. Appl. 302, No. 2, 484-501 (2005). Reviewer: Victor V. Goryainov (Volzhsky) MSC: 30C55 46F12 PDF BibTeX XML Cite \textit{R. O. Bauer}, J. Math. Anal. Appl. 302, No. 2, 484--501 (2005; Zbl 1067.30035) Full Text: DOI arXiv OpenURL
Winkler, H. Small perturbations of canonical systems. (English) Zbl 0969.34070 Integral Equations Oper. Theory 38, No. 2, 222-250 (2000). MSC: 34L05 34B20 34A55 47E05 47B25 PDF BibTeX XML Cite \textit{H. Winkler}, Integral Equations Oper. Theory 38, No. 2, 222--250 (2000; Zbl 0969.34070) Full Text: DOI OpenURL
Langer, Heinz; Winkler, Henrik Direct and inverse spectral problems for generalized strings. (English) Zbl 0898.34076 Integral Equations Oper. Theory 30, No. 4, 409-431 (1998). MSC: 34L15 47B25 47E05 34A55 34M50 PDF BibTeX XML Cite \textit{H. Langer} and \textit{H. Winkler}, Integral Equations Oper. Theory 30, No. 4, 409--431 (1998; Zbl 0898.34076) Full Text: DOI OpenURL
Winkler, H. The inverse spectral problem for canonical systems. (English) Zbl 0843.34031 Integral Equations Oper. Theory 22, No. 3, 360-374 (1995). Reviewer: A.Strauss (Ul’yanovsk) MSC: 34B20 34A55 47A75 47B25 PDF BibTeX XML Cite \textit{H. Winkler}, Integral Equations Oper. Theory 22, No. 3, 360--374 (1995; Zbl 0843.34031) Full Text: DOI OpenURL
Van Assche, Walter Christoffel functions and Turán determinants on several intervals. (English) Zbl 0790.42013 J. Comput. Appl. Math. 48, No. 1-2, 207-223 (1993). MSC: 42C05 PDF BibTeX XML Cite \textit{W. Van Assche}, J. Comput. Appl. Math. 48, No. 1--2, 207--223 (1993; Zbl 0790.42013) Full Text: DOI OpenURL
Schumacher, J. M. A pointwise criterion for controller robustness. (English) Zbl 0743.93080 Syst. Control Lett. 18, No. 1, 1-8 (1992). MSC: 93D09 PDF BibTeX XML Cite \textit{J. M. Schumacher}, Syst. Control Lett. 18, No. 1, 1--8 (1992; Zbl 0743.93080) Full Text: DOI OpenURL
Nagy, B. Local spectral theory. (English) Zbl 0425.47002 Acta Math. Acad. Sci. Hung. 37, 433-443 (1981). MSC: 47A10 47B25 47A15 PDF BibTeX XML Cite \textit{B. Nagy}, Acta Math. Acad. Sci. Hung. 37, 433--443 (1981; Zbl 0425.47002) Full Text: DOI OpenURL
Fröhlich, J. Unbounded, symmetric semigroups on a separable Hilbert space are essentially selfadjoint. (English) Zbl 0452.47043 Adv. Appl. Math. 1, 237-250 (1980). MSC: 47D03 47B25 PDF BibTeX XML Cite \textit{J. Fröhlich}, Adv. Appl. Math. 1, 237--256 (1980; Zbl 0452.47043) Full Text: DOI OpenURL
Tippenhauer, Ulrich Approximation von Operatorgleichungen mit Reprokernen. (German) Zbl 0424.41018 Appl. Anal. 9, 179-189 (1979). MSC: 41A30 41A63 41A25 PDF BibTeX XML Cite \textit{U. Tippenhauer}, Appl. Anal. 9, 179--189 (1979; Zbl 0424.41018) Full Text: DOI OpenURL
Kaballo, Winfried; Schneider, Albert On the spectral kernel of symmetric extensions. (English) Zbl 0422.47011 Manuscr. Math. 29, 113-118 (1979). MSC: 47B25 47A10 47E05 PDF BibTeX XML Cite \textit{W. Kaballo} and \textit{A. Schneider}, Manuscr. Math. 29, 113--118 (1979; Zbl 0422.47011) Full Text: DOI EuDML OpenURL
Daho, K.; Langer, H. Sturm-Liouville operators with an indefinite weight function. (English) Zbl 0372.34018 Proc. R. Soc. Edinb., Sect. A 78, 161-191 (1977). MSC: 34L99 PDF BibTeX XML Cite \textit{K. Daho} and \textit{H. Langer}, Proc. R. Soc. Edinb., Sect. A, Math. 78, 161--191 (1977; Zbl 0372.34018) Full Text: DOI OpenURL
Ruijsenaars, S. N. M.; Bongaarts, P. J. M. Scattering theory for one-dimensional step potentials. (English) Zbl 0353.47004 Ann. Inst. Henri Poincaré, Nouv. Sér., Sect. A 26, 1-17 (1977). MSC: 47A40 35J10 35B25 35P25 PDF BibTeX XML Cite \textit{S. N. M. Ruijsenaars} and \textit{P. J. M. Bongaarts}, Ann. Inst. Henri Poincaré, Nouv. Sér., Sect. A 26, 1--17 (1977; Zbl 0353.47004) Full Text: Numdam EuDML OpenURL
Arnold, Ludwig Deterministic version of Wigner’s semicircle law for the distribution of matrix eigenvalues. (English) Zbl 0332.15009 Linear Algebra Appl. 13, 185-199 (1976). MSC: 15A42 60H99 PDF BibTeX XML Cite \textit{L. Arnold}, Linear Algebra Appl. 13, 185--199 (1976; Zbl 0332.15009) Full Text: DOI OpenURL
Borchers, H. J.; Yngvason, J. On the algebra of field operators. The weak commutant and integral decompositions of states. (English) Zbl 0307.46053 Commun. Math. Phys. 42, 231-252 (1975). MSC: 46N99 46J25 46F05 46L10 46L05 PDF BibTeX XML Cite \textit{H. J. Borchers} and \textit{J. Yngvason}, Commun. Math. Phys. 42, 231--252 (1975; Zbl 0307.46053) Full Text: DOI OpenURL
Voigt, Jürgen Über die Friedrichsfortsetzung und die Monotonie der Eigenwerte. (German) Zbl 0305.47026 Arch. Math. 26, 183-188 (1975). MSC: 47F05 47A20 35P15 47A10 PDF BibTeX XML Cite \textit{J. Voigt}, Arch. Math. 26, 183--188 (1975; Zbl 0305.47026) Full Text: DOI OpenURL
Dijksma, A.; de Snoo, H. S. V. Eigenfunction expansions for nondensely defined differential operators. (English) Zbl 0299.47023 J. Differ. Equations 17, 198-219 (1975). MSC: 47B25 34L99 47E05 47A70 PDF BibTeX XML Cite \textit{A. Dijksma} and \textit{H. S. V. de Snoo}, J. Differ. Equations 17, 198--219 (1975; Zbl 0299.47023) Full Text: DOI OpenURL
Graffi, S.; Grecchi, V. Matrix moment methods in perturbation theory, boson quantum field models, and anharmonic oscillators. (English) Zbl 0324.47010 Commun. Math. Phys. 35, 235-252 (1974). MSC: 47A55 44A60 47A40 47A10 PDF BibTeX XML Cite \textit{S. Graffi} and \textit{V. Grecchi}, Commun. Math. Phys. 35, 235--252 (1974; Zbl 0324.47010) Full Text: DOI OpenURL
Scarpellini, B. On the spectra of certain semi-groups. (English) Zbl 0291.47021 Math. Ann. 211, 323-336 (1974). MSC: 47D03 47A10 28D05 PDF BibTeX XML Cite \textit{B. Scarpellini}, Math. Ann. 211, 323--336 (1974; Zbl 0291.47021) Full Text: DOI EuDML OpenURL
Kersting, Götz Strong ratio limit property and R-recurrence of reversible Markov chains. (English) Zbl 0283.60071 Z. Wahrscheinlichkeitstheor. Verw. Geb. 30, 343-356 (1974). MSC: 60G50 60F99 PDF BibTeX XML Cite \textit{G. Kersting}, Z. Wahrscheinlichkeitstheor. Verw. Geb. 30, 343--356 (1974; Zbl 0283.60071) Full Text: DOI OpenURL
Textorius, Björn Über Störungen kanonischer Differentialgleichungen mit operatorwertigen Koeffizienten und definisierbarem Monodromieoperator. (German) Zbl 0283.34060 Math. Z. 137, 311-342 (1974). MSC: 34G99 47E05 PDF BibTeX XML Cite \textit{B. Textorius}, Math. Z. 137, 311--342 (1974; Zbl 0283.34060) Full Text: DOI EuDML OpenURL
Putnam, C. R. Hyponormal operators having real parts with simple spectra. (English) Zbl 0254.47039 Trans. Am. Math. Soc. 172(1972), 447-464 (1973). MSC: 47B20 PDF BibTeX XML Cite \textit{C. R. Putnam}, Trans. Am. Math. Soc. 172, 447--464 (1973; Zbl 0254.47039) Full Text: DOI OpenURL
Gilbert, Richard C. Simplicity of linear ordinary differential operators. (English) Zbl 0222.34058 J. Differ. Equations 11, 672-681 (1972). MSC: 34G10 PDF BibTeX XML Cite \textit{R. C. Gilbert}, J. Differ. Equations 11, 672--681 (1972; Zbl 0222.34058) Full Text: DOI OpenURL
Langer, Heinz Verallgemeinerte Resolventen eines J-nichtnegativen Operators mit endlichem Defekt. (Generalized resolvents of a J-nonnegative operator with finite defect.). (German) Zbl 0232.47008 J. Funct. Anal. 8, 287-320 (1971). MSC: 47A10 47A20 47E05 PDF BibTeX XML Cite \textit{H. Langer}, J. Funct. Anal. 8, 287--320 (1971; Zbl 0232.47008) Full Text: DOI OpenURL
Weidmann, J. Oszillationsmethoden für Systeme gewöhnlicher Differentialgleichungen. (German) Zbl 0206.10002 Math. Z. 119, 349-373 (1971). MSC: 34C15 34L40 PDF BibTeX XML Cite \textit{J. Weidmann}, Math. Z. 119, 349--373 (1971; Zbl 0206.10002) Full Text: DOI EuDML OpenURL
Schneider, Albert Zum Entwicklungssatz bei reellen singulären Differentialgleichungssystemen. (German) Zbl 0201.10502 Arch. Math. 21, 192-197 (1970). PDF BibTeX XML Cite \textit{A. Schneider}, Arch. Math. 21, 192--197 (1970; Zbl 0201.10502) Full Text: DOI OpenURL
Henrici, Peter; Troesch, B. Andrew; Wuytack, Luc Sloshing frequencies for a half-space with circular or strip-like aperture. (English) Zbl 0199.21001 Z. Angew. Math. Phys. 21, 285-318 (1970). PDF BibTeX XML Cite \textit{P. Henrici} et al., Z. Angew. Math. Phys. 21, 285--318 (1970; Zbl 0199.21001) Full Text: DOI OpenURL
Gilbert, R. C. Symmetric operators with twice continuously differentiable spectral functions. (English) Zbl 0183.14004 Proc. Am. Math. Soc. 23, 347-355 (1969). PDF BibTeX XML Cite \textit{R. C. Gilbert}, Proc. Am. Math. Soc. 23, 347--355 (1969; Zbl 0183.14004) Full Text: DOI OpenURL
Hackenbroch, Wolfgang Integraldarstellung einer Klasse dissipativer linearer Operatoren. (German) Zbl 0179.17901 Math. Z. 109, 273-287 (1969). PDF BibTeX XML Cite \textit{W. Hackenbroch}, Math. Z. 109, 273--287 (1969; Zbl 0179.17901) Full Text: DOI EuDML OpenURL
Gilbert, R. C. Symmetric operators with singular spectral functions. (English) Zbl 0174.18104 Proc. Am. Math. Soc. 21, 43-49 (1969). PDF BibTeX XML Cite \textit{R. C. Gilbert}, Proc. Am. Math. Soc. 21, 43--49 (1969; Zbl 0174.18104) Full Text: DOI OpenURL
Luft, E. The two-sided closed ideals of the algebra of bounded linear operators of a Hilbert space. (English) Zbl 0197.11301 Czech. Math. J. 18(93), 595-605 (1968). PDF BibTeX XML Cite \textit{E. Luft}, Czech. Math. J. 18(93), 595--605 (1968; Zbl 0197.11301) Full Text: EuDML OpenURL
van Winter, C. Orbital angular momentum and group representations. (English) Zbl 0162.58504 Ann. Phys. 47, 232-274 (1968). PDF BibTeX XML Cite \textit{C. van Winter}, Ann. Phys. 47, 232--274 (1968; Zbl 0162.58504) Full Text: DOI OpenURL
Schrader, R. On the existence of a local Hamiltonian in the Galilean invariant Lee Model. (English) Zbl 0159.59902 Commun. Math. Phys. 10, 155-178 (1968). PDF BibTeX XML Cite \textit{R. Schrader}, Commun. Math. Phys. 10, 155--178 (1968; Zbl 0159.59902) Full Text: DOI OpenURL
Gilbert, R. C. Spectral multiplicity of selfadjoint dilations. (English) Zbl 0155.46202 Proc. Am. Math. Soc. 19, 477-482 (1968). PDF BibTeX XML Cite \textit{R. C. Gilbert}, Proc. Am. Math. Soc. 19, 477--482 (1968; Zbl 0155.46202) Full Text: DOI OpenURL
Kuhnert, F. Über die relativ gleichmäßige Konvergenz abgeschlossener Operatoren. (German) Zbl 0153.16902 Math. Ann. 175, 132-145 (1968). PDF BibTeX XML Cite \textit{F. Kuhnert}, Math. Ann. 175, 132--145 (1968; Zbl 0153.16902) Full Text: DOI EuDML OpenURL
Douglas, R. G. On majorization, factorization, and range inclusion of operators on Hilbert space. (English) Zbl 0146.12503 Proc. Am. Math. Soc. 17, 413-415 (1966). PDF BibTeX XML Cite \textit{R. G. Douglas}, Proc. Am. Math. Soc. 17, 413--415 (1966; Zbl 0146.12503) Full Text: DOI OpenURL
Jänich, Klaus Vektorraumbündel und der Raum der Fredholm-Operatoren. (German) Zbl 0148.12401 Math. Ann. 161, 129-142 (1965). PDF BibTeX XML Cite \textit{K. Jänich}, Math. Ann. 161, 129--142 (1965; Zbl 0148.12401) Full Text: DOI EuDML OpenURL
McKelvey, Robert Spectral measures, generalized resolvents, and functions of positive type. (English) Zbl 0146.12604 J. Math. Anal. Appl. 11, 447-477 (1965). PDF BibTeX XML Cite \textit{R. McKelvey}, J. Math. Anal. Appl. 11, 447--477 (1965; Zbl 0146.12604) Full Text: DOI OpenURL
Rampacher, H.; Stumpf, H.; Wagner, F. Grundlagen der Dynamik in der nichtlinearen Spinortheorie der Elementarteilchen. (German) Zbl 0133.23306 Fortschr. Phys. 13, 385-480 (1965). PDF BibTeX XML Cite \textit{H. Rampacher} et al., Fortschr. Phys. 13, 385--480 (1965; Zbl 0133.23306) Full Text: DOI OpenURL
Kaniel, S. Unbounded normal operators in Hilbert space. (English) Zbl 0197.10103 Trans. Am. Math. Soc. 113, 488-511 (1964). PDF BibTeX XML Cite \textit{S. Kaniel}, Trans. Am. Math. Soc. 113, 488--511 (1964; Zbl 0197.10103) Full Text: DOI OpenURL
Pincus, J. D. On the spectral theory of singular integral operators. (English) Zbl 0152.14101 Trans. Am. Math. Soc. 113, 101-128 (1964). PDF BibTeX XML Cite \textit{J. D. Pincus}, Trans. Am. Math. Soc. 113, 101--128 (1964; Zbl 0152.14101) Full Text: DOI OpenURL
Wloka, Josef Limesräume und Distributionen. (German) Zbl 0173.41902 Math. Ann. 152, 351-409 (1963). PDF BibTeX XML Cite \textit{J. Wloka}, Math. Ann. 152, 351--409 (1963; Zbl 0173.41902) Full Text: DOI EuDML OpenURL
Carroll, Robert W. Problems in linked operators. I. (English) Zbl 0123.31103 Math. Ann. 151, 272-282 (1963). Reviewer: W. Gerisch MSC: 35R20 47-XX PDF BibTeX XML Cite \textit{R. W. Carroll}, Math. Ann. 151, 272--282 (1963; Zbl 0123.31103) Full Text: DOI EuDML OpenURL
Dahlquist, Germund G. A special stability problem for linear multistep methods. (English) Zbl 0123.11703 BIT, Nord. Tidskr. Inf.-behandl. 3, 27-43 (1963). PDF BibTeX XML Cite \textit{G. G. Dahlquist}, BIT, Nord. Tidskr. Inf.-behandl. 3, 27--43 (1963; Zbl 0123.11703) Full Text: DOI OpenURL
Borchers, H.-J. On structure of the algebra of field operators. (English) Zbl 0129.42205 Nuovo Cimento, X. Ser. 24, 214-236 (1962). PDF BibTeX XML Cite \textit{H. J. Borchers}, Nuovo Cimento, X. Ser. 24, 214--236 (1962; Zbl 0129.42205) Full Text: DOI OpenURL
Langer, H. Zur Spektraltheorie J-selbstadjungierter Operatoren. (German) Zbl 0119.32003 Math. Ann. 146, 60-85 (1962). PDF BibTeX XML Cite \textit{H. Langer}, Math. Ann. 146, 60--85 (1962; Zbl 0119.32003) Full Text: DOI EuDML OpenURL
Hildebrandt, S. Rand- und Eigenwertaufgaben bei stark elliptischen Systemen linearer Differentialgleichungen. (German) Zbl 0114.05404 Math. Ann. 148, 411-429 (1962). PDF BibTeX XML Cite \textit{S. Hildebrandt}, Math. Ann. 148, 411--429 (1962; Zbl 0114.05404) Full Text: DOI EuDML OpenURL
Heble, M. P. A regression problem concerning stationary processes. (English) Zbl 0212.21202 Trans. Am. Math. Soc. 99, 350-371 (1961). MSC: 62M10 62F12 PDF BibTeX XML Cite \textit{M. P. Heble}, Trans. Am. Math. Soc. 99, 350--371 (1961; Zbl 0212.21202) Full Text: DOI OpenURL
Reid, William T. Oscillation criteria for selfadjoint differential systems. (English) Zbl 0114.29202 Trans. Am. Math. Soc. 101, 91-106 (1961). PDF BibTeX XML Cite \textit{W. T. Reid}, Trans. Am. Math. Soc. 101, 91--106 (1961; Zbl 0114.29202) Full Text: DOI OpenURL
Nieto, José Charakterisierung der elliptischen Differentialoperatoren. (German) Zbl 0116.07403 Math. Ann. 141, 22-42 (1960). PDF BibTeX XML Cite \textit{J. Nieto}, Math. Ann. 141, 22--42 (1960; Zbl 0116.07403) Full Text: DOI EuDML OpenURL
Coddington, E. A.; Gilbert, R. C. Generalized resolvents of ordinary differential operators. (English) Zbl 0137.32202 Trans. Am. Math. Soc. 93, 216-241 (1959). PDF BibTeX XML Cite \textit{E. A. Coddington} and \textit{R. C. Gilbert}, Trans. Am. Math. Soc. 93, 216--241 (1959; Zbl 0137.32202) Full Text: DOI OpenURL
Devinatz, Allen On the extensions of positive definite functions. (English) Zbl 0100.10601 Acta Math. 102, 109-134 (1959). PDF BibTeX XML Cite \textit{A. Devinatz}, Acta Math. 102, 109--134 (1959; Zbl 0100.10601) Full Text: DOI OpenURL
Koppelman, W.; Pincus, J. D. Spectral representations for finite Hilbert transformations. (English) Zbl 0085.31701 Math. Z. 71, 399-407 (1959). PDF BibTeX XML Cite \textit{W. Koppelman} and \textit{J. D. Pincus}, Math. Z. 71, 399--407 (1959; Zbl 0085.31701) Full Text: DOI EuDML Backlinks: MO OpenURL
Kato, Tosio Perturbation theory for nullity, deficiency and other quantities of linear operators. (English) Zbl 0090.09003 J. Anal. Math. 6, 261-322 (1958). PDF BibTeX XML Cite \textit{T. Kato}, J. Anal. Math. 6, 261--322 (1958; Zbl 0090.09003) Full Text: DOI OpenURL
Vidav, Ivan Über die Darstellung der positiven Funktionale. (German) Zbl 0080.10101 Math. Z. 68, 362-366 (1958). PDF BibTeX XML Cite \textit{I. Vidav}, Math. Z. 68, 362--366 (1958; Zbl 0080.10101) Full Text: DOI EuDML OpenURL