Diblík, Josef A criterion for existence of positive solutions of systems of retarded functional differential equations. (English) Zbl 0935.34061 Nonlinear Anal., Theory Methods Appl. 38, No. 3, A, 327-339 (1999). Reviewer: R.R.Akhmerov (Novosibirsk) MSC: 34K12 34K05 PDFBibTeX XMLCite \textit{J. Diblík}, Nonlinear Anal., Theory Methods Appl. 38, No. 3, 327--339 (1999; Zbl 0935.34061) Full Text: DOI
Bianchi, Gabriele; Pan, Xing-Bin Yamabe equations on half-spaces. (English) Zbl 0941.35025 Nonlinear Anal., Theory Methods Appl. 37, No. 2, A, 161-186 (1999). Reviewer: Marco Biroli (Monza) MSC: 35J60 35B33 PDFBibTeX XMLCite \textit{G. Bianchi} and \textit{X.-B. Pan}, Nonlinear Anal., Theory Methods Appl. 37, No. 2, 161--186 (1999; Zbl 0941.35025) Full Text: DOI
Choi, Q. Heung; Jung, Tacksun A nonlinear suspension bridge equation with nonconstant load. (English) Zbl 0934.74031 Nonlinear Anal., Theory Methods Appl. 35, No. 6, A, 649-668 (1999). Reviewer: W.Walter (Karlsruhe) MSC: 74H10 74K10 35Q72 PDFBibTeX XMLCite \textit{Q. H. Choi} and \textit{T. Jung}, Nonlinear Anal., Theory Methods Appl. 35, No. 6, 649--668 (1999; Zbl 0934.74031) Full Text: DOI
Yang, Z. P.; Pao, C. V. Positive solutions and dynamics of some reaction diffusion models in HIV transmission. (English) Zbl 0914.92022 Nonlinear Anal., Theory Methods Appl. 35, No. 3, A, 323-341 (1999). Reviewer: I.Onciulescu (Iaşi) MSC: 92D30 35Q92 PDFBibTeX XMLCite \textit{Z. P. Yang} and \textit{C. V. Pao}, Nonlinear Anal., Theory Methods Appl. 35, No. 3, 323--341 (1999; Zbl 0914.92022) Full Text: DOI
Nieto, Juan J. An abstract monotone iterative technique. (English) Zbl 0883.47058 Nonlinear Anal., Theory Methods Appl. 28, No. 12, 1923-1933 (1997). Reviewer: W.C.Rheinboldt (Pittsburgh) MSC: 47H07 47J25 PDFBibTeX XMLCite \textit{J. J. Nieto}, Nonlinear Anal., Theory Methods Appl. 28, No. 12, 1923--1933 (1997; Zbl 0883.47058) Full Text: DOI
Lair, Alan V.; Shaker, Aihua W. Uniqueness of solution to a singular quasilinear elliptic problem. (English) Zbl 0864.35043 Nonlinear Anal., Theory Methods Appl. 28, No. 3, 489-493 (1997). Reviewer: K.Pflüger (Berlin) MSC: 35J70 35B05 PDFBibTeX XMLCite \textit{A. V. Lair} and \textit{A. W. Shaker}, Nonlinear Anal., Theory Methods Appl. 28, No. 3, 489--493 (1997; Zbl 0864.35043) Full Text: DOI
Maia, Liliane A. Symmetry of internal waves. (English) Zbl 0872.76020 Nonlinear Anal., Theory Methods Appl. 28, No. 1, 87-102 (1997). Reviewer: A.V.Gemintern (Haifa) MSC: 76B55 76B25 35Q51 76V05 PDFBibTeX XMLCite \textit{L. A. Maia}, Nonlinear Anal., Theory Methods Appl. 28, No. 1, 87--102 (1997; Zbl 0872.76020) Full Text: DOI
Garcia-Melián, J.; Sabina de Lis, J. The behaviour of stationary solutions to some nonlinear diffusion problems. (English) Zbl 0894.35009 Nonlinear Anal., Theory Methods Appl. 30, No. 8, 5499-5504 (1997). Reviewer: I.Ginchev (Varna) MSC: 35B40 35J65 PDFBibTeX XMLCite \textit{J. Garcia-Melián} and \textit{J. Sabina de Lis}, Nonlinear Anal., Theory Methods Appl. 30, No. 8, 5499--5504 (1997; Zbl 0894.35009) Full Text: DOI
Wong, Patricia J. Y. Positive solutions of discrete \((n,p)\) boundary value problems. (English) Zbl 0893.39001 Nonlinear Anal., Theory Methods Appl. 30, No. 1, 377-388 (1997). Reviewer: D.Bobrowski (Poznań) MSC: 39A10 PDFBibTeX XMLCite \textit{P. J. Y. Wong}, Nonlinear Anal., Theory Methods Appl. 30, No. 1, 377--388 (1997; Zbl 0893.39001) Full Text: DOI
Huang, Lihong Boundedness of solutions for some nonlinear differential systems. (English) Zbl 0883.34042 Nonlinear Anal., Theory Methods Appl. 29, No. 7, 839-848 (1997). Reviewer: J.Ohriska (Košice) MSC: 34C11 34A34 PDFBibTeX XMLCite \textit{L. Huang}, Nonlinear Anal., Theory Methods Appl. 29, No. 7, 839--848 (1997; Zbl 0883.34042) Full Text: DOI
Agarwal, Ravi P.; O’Regan, Donal Some new existence results for differential and integral equations. (English) Zbl 0878.45001 Nonlinear Anal., Theory Methods Appl. 29, No. 6, 679-692 (1997). Reviewer: P.Talpalaru (Iaşi) MSC: 45G10 34B15 34K05 45M20 45G05 PDFBibTeX XMLCite \textit{R. P. Agarwal} and \textit{D. O'Regan}, Nonlinear Anal., Theory Methods Appl. 29, No. 6, 679--692 (1997; Zbl 0878.45001) Full Text: DOI
Chern, Jann-Long On the solution structures of the semilinear elliptic equations on \(\mathbb{R}^ n\). (English) Zbl 0877.35039 Nonlinear Anal., Theory Methods Appl. 28, No. 10, 1741-1750 (1997). Reviewer: M.Kučera (Praha) MSC: 35J60 35B40 PDFBibTeX XMLCite \textit{J.-L. Chern}, Nonlinear Anal., Theory Methods Appl. 28, No. 10, 1741--1750 (1997; Zbl 0877.35039) Full Text: DOI
Du, Yihong Bifurcation from semitrivial solution bundles and applications to certain equation systems. (English) Zbl 0884.47041 Nonlinear Anal., Theory Methods Appl. 27, No. 12, 1407-1435 (1996). Reviewer: A.Rodkina (Voronezh) MSC: 47J05 PDFBibTeX XMLCite \textit{Y. Du}, Nonlinear Anal., Theory Methods Appl. 27, No. 12, 1407--1435 (1996; Zbl 0884.47041) Full Text: DOI
Panda, Ratikanta On semilinear Neumann problems with critical growth for the \(n\)-Laplacian. (English) Zbl 0854.35045 Nonlinear Anal., Theory Methods Appl. 26, No. 8, 1347-1366 (1996). Reviewer: M.Biroli (Monza) MSC: 35J65 35J20 35B32 PDFBibTeX XMLCite \textit{R. Panda}, Nonlinear Anal., Theory Methods Appl. 26, No. 8, 1347--1366 (1996; Zbl 0854.35045) Full Text: DOI
Yang, Shu Lang Quasidifferentiability and positive solutions of equations for set-valued mappings. (English) Zbl 0867.47037 Nonlinear Anal., Theory Methods Appl. 25, No. 5, 487-498 (1995). Reviewer: S.L.Singh (Rishikesh) MSC: 47H04 47H10 54C60 46G05 47H09 49J50 47H07 PDFBibTeX XMLCite \textit{S. L. Yang}, Nonlinear Anal., Theory Methods Appl. 25, No. 5, 487--498 (1995; Zbl 0867.47037) Full Text: DOI
Janus, J.; Myjak, J. A generalized Emden-Fowler equation with a negative exponent. (English) Zbl 0819.34016 Nonlinear Anal., Theory Methods Appl. 23, No. 8, 953-970 (1994). Reviewer: W.Šeda (Bratislava) MSC: 34B15 34B27 65L10 PDFBibTeX XMLCite \textit{J. Janus} and \textit{J. Myjak}, Nonlinear Anal., Theory Methods Appl. 23, No. 8, 953--970 (1994; Zbl 0819.34016) Full Text: DOI
Allegretto, W.; Nistri, P. Existence and stability for nonpositone elliptic problems. (English) Zbl 0814.35030 Nonlinear Anal., Theory Methods Appl. 23, No. 10, 1243-1253 (1994). Reviewer: J.Hernandez (Madrid) MSC: 35J65 35P30 47H11 35B45 PDFBibTeX XMLCite \textit{W. Allegretto} and \textit{P. Nistri}, Nonlinear Anal., Theory Methods Appl. 23, No. 10, 1243--1253 (1994; Zbl 0814.35030) Full Text: DOI
Zhao, Zengqin Uniqueness of positive solutions for singular nonlinear second-order boundary-value problems. (English) Zbl 0813.34026 Nonlinear Anal., Theory Methods Appl. 23, No. 6, 755-765 (1994). Reviewer: I.Rachůnková (Olomouc) MSC: 34B15 PDFBibTeX XMLCite \textit{Z. Zhao}, Nonlinear Anal., Theory Methods Appl. 23, No. 6, 755--765 (1994; Zbl 0813.34026) Full Text: DOI
Li, Horng Jaan; Yeh, Cheh Chih Existence of positive nondecreasing solutions of nonlinear difference equations. (English) Zbl 0805.39004 Nonlinear Anal., Theory Methods Appl. 22, No. 10, 1271-1284 (1994). Reviewer: V.I.Tkachenko (Kiev) MSC: 39A10 PDFBibTeX XMLCite \textit{H. J. Li} and \textit{C. C. Yeh}, Nonlinear Anal., Theory Methods Appl. 22, No. 10, 1271--1284 (1994; Zbl 0805.39004) Full Text: DOI
Ruan, Weihua Asymptotic behavior and positive steady-state solutions of a reaction- diffusion model with autocatalysis and saturation law. (English) Zbl 0796.35074 Nonlinear Anal., Theory Methods Appl. 21, No. 6, 439-456 (1993). Reviewer: G.Hetzer (Auburn) MSC: 35K57 35K60 35P30 35B32 PDFBibTeX XMLCite \textit{W. Ruan}, Nonlinear Anal., Theory Methods Appl. 21, No. 6, 439--456 (1993; Zbl 0796.35074) Full Text: DOI
Torrejón, Ricardo Positive almost periodic solutions of a state-dependent delay nonlinear integral equation. (English) Zbl 0787.45003 Nonlinear Anal., Theory Methods Appl. 20, No. 12, 1383-1416 (1993). Reviewer: M.-C.Anisiu (Cluj-Napoca) MSC: 45G10 45M15 PDFBibTeX XMLCite \textit{R. Torrejón}, Nonlinear Anal., Theory Methods Appl. 20, No. 12, 1383--1416 (1993; Zbl 0787.45003) Full Text: DOI
Wong, Fu-Hsiang Existence of positive solutions of singular boundary value problems. (English) Zbl 0790.34026 Nonlinear Anal., Theory Methods Appl. 21, No. 5, 397-406 (1993). Reviewer: R.Precup (Cluj-Napoca) MSC: 34B15 35J25 PDFBibTeX XMLCite \textit{F.-H. Wong}, Nonlinear Anal., Theory Methods Appl. 21, No. 5, 397--406 (1993; Zbl 0790.34026) Full Text: DOI
Habets, P.; Ramos, M.; Sanchez, L. Jumping nonlinearities for Neumann BVPs with positive forcing. (English) Zbl 0772.34025 Nonlinear Anal., Theory Methods Appl. 20, No. 5, 533-549 (1993). Reviewer: R.Precup (Cluj-Napoca) MSC: 34B15 34B24 PDFBibTeX XMLCite \textit{P. Habets} et al., Nonlinear Anal., Theory Methods Appl. 20, No. 5, 533--549 (1993; Zbl 0772.34025) Full Text: DOI
Noussair, Ezzat S.; Swanson, Charles A.; Yang, Jianfu Quasilinear elliptic problems with critical exponents. (English) Zbl 0785.35042 Nonlinear Anal., Theory Methods Appl. 20, No. 3, 285-301 (1993). Reviewer: J.Madjarova (Göteborg) MSC: 35J65 35J35 35D05 PDFBibTeX XMLCite \textit{E. S. Noussair} et al., Nonlinear Anal., Theory Methods Appl. 20, No. 3, 285--301 (1993; Zbl 0785.35042) Full Text: DOI
Wang, Xujia Sharp constant in a Sobolev inequality. (English) Zbl 0803.35045 Nonlinear Anal., Theory Methods Appl. 20, No. 3, 261-268 (1993). MSC: 35J60 35J30 35B45 PDFBibTeX XMLCite \textit{X. Wang}, Nonlinear Anal., Theory Methods Appl. 20, No. 3, 261--268 (1993; Zbl 0803.35045) Full Text: DOI
Cheng, Sui Sun; Patula, William T. An existence theorem for a nonlinear difference equation. (English) Zbl 0774.39001 Nonlinear Anal., Theory Methods Appl. 20, No. 3, 193-203 (1993). Reviewer: A.D.Mednykh (Novosibirsk) MSC: 39A10 PDFBibTeX XMLCite \textit{S. S. Cheng} and \textit{W. T. Patula}, Nonlinear Anal., Theory Methods Appl. 20, No. 3, 193--203 (1993; Zbl 0774.39001) Full Text: DOI
Tineo, Antonio Existence of global coexistence state for periodic competition diffusion systems. (English) Zbl 0779.35058 Nonlinear Anal., Theory Methods Appl. 19, No. 4, 335-344 (1992). Reviewer: Y.Ebihara (Fukuoka) MSC: 35K57 35B40 35B35 35D05 PDFBibTeX XMLCite \textit{A. Tineo}, Nonlinear Anal., Theory Methods Appl. 19, No. 4, 335--344 (1992; Zbl 0779.35058) Full Text: DOI
Guo, Zongming Solvability of some singular nonlinear boundary value problems and existence of positive radial solutions of some nonlinear elliptic problems. (English) Zbl 0737.35024 Nonlinear Anal., Theory Methods Appl. 16, No. 9, 781-790 (1991). Reviewer: O.John (Praha) MSC: 35J65 34B15 47H11 PDFBibTeX XMLCite \textit{Z. Guo}, Nonlinear Anal., Theory Methods Appl. 16, No. 9, 781--790 (1991; Zbl 0737.35024) Full Text: DOI
Kwong, Man Kam Uniqueness results for Emden-Fowler boundary value problems. (English) Zbl 0744.34023 Nonlinear Anal., Theory Methods Appl. 16, No. 5, 435-454 (1991). Reviewer: P.Zezza (Firenze) MSC: 34B15 68W30 PDFBibTeX XMLCite \textit{M. K. Kwong}, Nonlinear Anal., Theory Methods Appl. 16, No. 5, 435--454 (1991; Zbl 0744.34023) Full Text: DOI
Timm, Uwe; Totaro, Silvia; Okubo, Akira Self- and mutual shading effect on competing algal distribution. (English) Zbl 0760.92023 Nonlinear Anal., Theory Methods Appl. 17, No. 6, 559-576 (1991). Reviewer: Y.Y.Sugai (Chiba-shi) MSC: 92D40 45K05 45N05 47H20 PDFBibTeX XMLCite \textit{U. Timm} et al., Nonlinear Anal., Theory Methods Appl. 17, No. 6, 559--576 (1991; Zbl 0760.92023) Full Text: DOI
Lin, Song-Sun On the number of positive solutions for nonlinear elliptic equations when a parameter is large. (English) Zbl 0731.35039 Nonlinear Anal., Theory Methods Appl. 16, No. 3, 283-297 (1991). Reviewer: J.Hernandez (Madrid) MSC: 35J65 35P30 35B25 35B05 PDFBibTeX XMLCite \textit{S.-S. Lin}, Nonlinear Anal., Theory Methods Appl. 16, No. 3, 283--297 (1991; Zbl 0731.35039) Full Text: DOI
Michalek, Ray Existence of a positive solution of a general quasilinear elliptic equation with a nonlinear boundary condition of mixed type. (English) Zbl 0731.35040 Nonlinear Anal., Theory Methods Appl. 15, No. 9, 871-882 (1990). Reviewer: M.Primicerio (Firenze) MSC: 35J65 58E05 PDFBibTeX XMLCite \textit{R. Michalek}, Nonlinear Anal., Theory Methods Appl. 15, No. 9, 871--882 (1990; Zbl 0731.35040) Full Text: DOI
Cao, Daomin Positive solution and bifurcation from the essential spectrum of a semilinear elliptic equation on \(R^ n\). (English) Zbl 0729.35049 Nonlinear Anal., Theory Methods Appl. 15, No. 11, 1045-1052 (1990). Reviewer: U.Göhner (Stuttgart) MSC: 35J65 35B32 58E07 PDFBibTeX XMLCite \textit{D. Cao}, Nonlinear Anal., Theory Methods Appl. 15, No. 11, 1045--1052 (1990; Zbl 0729.35049) Full Text: DOI
Györi, I. Comparison results for integro-differential equations of Volterra type. (English) Zbl 0723.45016 Nonlinear Anal., Theory Methods Appl. 15, No. 3, 245-252 (1990). Reviewer: O.Staffans (Espoo) MSC: 45J05 26D10 45M20 PDFBibTeX XMLCite \textit{I. Györi}, Nonlinear Anal., Theory Methods Appl. 15, No. 3, 245--252 (1990; Zbl 0723.45016) Full Text: DOI
Senba, Takasi; Ebihara, Yukiyoshi; Furusho, Yasuhiro Dirichlet problem for a semilinear elliptic equation with singular coefficient. (English) Zbl 0711.35048 Nonlinear Anal., Theory Methods Appl. 15, No. 4, 299-306 (1990). Reviewer: M.A.Vivaldi MSC: 35J65 PDFBibTeX XMLCite \textit{T. Senba} et al., Nonlinear Anal., Theory Methods Appl. 15, No. 4, 299--306 (1990; Zbl 0711.35048) Full Text: DOI
Rother, W. Existence theorems for a nonlinear elliptic eigenvalue problem on \({\mathbb{R}}^ N\). (English) Zbl 0709.35043 Nonlinear Anal., Theory Methods Appl. 15, No. 4, 381-386 (1990). Reviewer: J.Hernandez MSC: 35J65 35P30 35J20 PDFBibTeX XMLCite \textit{W. Rother}, Nonlinear Anal., Theory Methods Appl. 15, No. 4, 381--386 (1990; Zbl 0709.35043) Full Text: DOI
Bertsch, Michiel; Ughi, Maura Positivity properties of viscosity solutions of a degenerate parabolic equation. (English) Zbl 0702.35044 Nonlinear Anal., Theory Methods Appl. 14, No. 7, 571-592 (1990). Reviewer: I.Vrabie MSC: 35B99 35K65 35K55 35K15 PDFBibTeX XMLCite \textit{M. Bertsch} and \textit{M. Ughi}, Nonlinear Anal., Theory Methods Appl. 14, No. 7, 571--592 (1990; Zbl 0702.35044) Full Text: DOI
Totaro, Silvia Mutual shading effect on algal distribution: A nonlinear problem. (English) Zbl 0721.92027 Nonlinear Anal., Theory Methods Appl. 13, No. 8, 969-986 (1989). Reviewer: Y.Y.Sugai (Chiba-shi) MSC: 92D40 45K05 47H20 92B99 45N05 PDFBibTeX XMLCite \textit{S. Totaro}, Nonlinear Anal., Theory Methods Appl. 13, No. 8, 969--986 (1989; Zbl 0721.92027) Full Text: DOI
Zhu, Xiping Multiple entire solutions of a semilinear elliptic equation. (English) Zbl 0671.35023 Nonlinear Anal., Theory Methods Appl. 12, No. 11, 1297-1316 (1988). Reviewer: M.Wiegner MSC: 35J60 35A05 35J20 PDFBibTeX XMLCite \textit{X. Zhu}, Nonlinear Anal., Theory Methods Appl. 12, No. 11, 1297--1316 (1988; Zbl 0671.35023) Full Text: DOI
Mirenghi, Elvira Equilibrium solutions of a semilinear reaction - diffusion system. (English) Zbl 0661.35041 Nonlinear Anal., Theory Methods Appl. 11, 393-405 (1987). Reviewer: J.E.Bouillet MSC: 35K55 92D25 35J60 35B35 PDFBibTeX XMLCite \textit{E. Mirenghi}, Nonlinear Anal., Theory Methods Appl. 11, 393--405 (1987; Zbl 0661.35041) Full Text: DOI
Rojas, Germán An inequality for the critical value of nonlinear eigenvalue problems. (English) Zbl 0658.35072 Nonlinear Anal., Theory Methods Appl. 11, 1257-1265 (1987). Reviewer: K.Chang MSC: 35P30 35J65 35B32 35B50 PDFBibTeX XMLCite \textit{G. Rojas}, Nonlinear Anal., Theory Methods Appl. 11, 1257--1265 (1987; Zbl 0658.35072) Full Text: DOI
Potra, Florian A. Newton-like methods with monotone convergence for solving nonlinear operator equations. (English) Zbl 0633.65050 Nonlinear Anal., Theory Methods Appl. 11, 697-717 (1987). Reviewer: B.Burrows MSC: 65J15 65L10 47J25 47H07 34B15 PDFBibTeX XMLCite \textit{F. A. Potra}, Nonlinear Anal., Theory Methods Appl. 11, 697--717 (1987; Zbl 0633.65050) Full Text: DOI
Swanson, Charles A. Positive solutions of \(-\Delta u=f(x,u)\). (English) Zbl 0638.35032 Nonlinear Anal., Theory Methods Appl. 9, 1319-1323 (1985). Reviewer: P.W.Schaefer MSC: 35J65 35B05 35J25 PDFBibTeX XMLCite \textit{C. A. Swanson}, Nonlinear Anal., Theory Methods Appl. 9, 1319--1323 (1985; Zbl 0638.35032) Full Text: DOI
Ôtani, Mitsuharu On certain second order ordinary differential equations associated with Sobolev-Poincaré-type inequalities. (English) Zbl 0559.35028 Nonlinear Anal., Theory Methods Appl. 8, 1255-1270 (1984). Reviewer: I.Ginchev MSC: 35J60 35J20 35B35 35B50 PDFBibTeX XMLCite \textit{M. Ôtani}, Nonlinear Anal., Theory Methods Appl. 8, 1255--1270 (1984; Zbl 0559.35028) Full Text: DOI
Furusho, Yasuhiro Existence and bifurcation of positive solutions of asymptotically linear elliptic equations in exterior domains. (English) Zbl 0548.35044 Nonlinear Anal., Theory Methods Appl. 8, 583-593 (1984). Reviewer: E.Dancer MSC: 35J60 35B32 PDFBibTeX XMLCite \textit{Y. Furusho}, Nonlinear Anal., Theory Methods Appl. 8, 583--593 (1984; Zbl 0548.35044) Full Text: DOI
Dancer, E. N. Uniqueness for elliptic equations when a parameter is large. (English) Zbl 0526.35032 Nonlinear Anal., Theory Methods Appl. 8, 835-836 (1984). MSC: 35J65 35A05 35B30 PDFBibTeX XMLCite \textit{E. N. Dancer}, Nonlinear Anal., Theory Methods Appl. 8, 835--836 (1984; Zbl 0526.35032) Full Text: DOI
Noussair, E. S.; Swanson, C. A. Semilinear Schrödinger equations in exterior domains. (English) Zbl 0452.35036 Nonlinear Anal., Theory Methods Appl. 4, 635-637 (1980). MSC: 35J65 35J10 35B05 PDFBibTeX XMLCite \textit{E. S. Noussair} and \textit{C. A. Swanson}, Nonlinear Anal., Theory Methods Appl. 4, 635--637 (1980; Zbl 0452.35036) Full Text: DOI
Seifert, George Positive invariance of closed sets for generalized Volterra equations. (English) Zbl 0426.45016 Nonlinear Anal., Theory Methods Appl. 4, 41-50 (1980). MSC: 45N05 45D05 34K30 34G20 45G10 PDFBibTeX XMLCite \textit{G. Seifert}, Nonlinear Anal., Theory Methods Appl. 4, 41--50 (1980; Zbl 0426.45016) Full Text: DOI
Busoni, Giorgio; Frosali, Giovanni; Belleni-Morante, Aldo A nonlinear problem of evolution arising from radiation transfer theory. (English) Zbl 0416.45008 Nonlinear Anal., Theory, Methods Appl. 3, 755-772 (1979). MSC: 45K05 82C70 85A25 47J05 47H20 47H07 PDFBibTeX XMLCite \textit{G. Busoni} et al., Nonlinear Anal., Theory Methods Appl. 3, 755--772 (1979; Zbl 0416.45008) Full Text: DOI