Benevieri P. - Calamai A. - Furi M. - Pera M.P., An infinite dimensional version of the intermediate value theorem, J. Fixed Point Theory Appl. (2023) 25:70 https://doi.org/10.1007/s11784-023-01073-9.

Benevieri P. - Calamai A. - Furi M. - Pera M.P., A degree associated to linear eigenvalue problems in Hilbert spaces and applications to nonlinear spectral theory,  J. Dyn. Diff. Equat. 34, 555–581 (2022). https://doi.org/10.1007/s10884-020-09921-9.

Benevieri P. - Calamai A. - Furi M. - Pera M.P., The Brouwer degree associated to classical eigenvalue problems and applications to nonlinear spectral theory,  Topol. Methods Nonlinear Anal. 59 (2022), 499--523. DOI: 10.12775/TMNA.2021.006 (preprint arXiv:1912.03182).
 

Benevieri P. - Calamai A. - Furi M. - Pera M.P.,  Global persistence of the unit eigenvectors of perturbed eigenvalue problems in Hilbert spaces: the odd multiplicity case, Mathematics 2021, 9(5), 561; Mathematics 2021, 9(5), 561; https://doi.org/10.3390/math9050561.

Benevieri P. - Calamai A. - Furi M. - Pera M.P., Global persistence of the unit eigenvectors of perturbed eigenvalue problems in Hilbert spaces, Z. Anal. Anwend. 39 (2020), no. 4, 475--497. DOI: 10.4171/ZAA/1669. 

Benevieri P. - Calamai A. - Furi M. - Pera M.P., Global continuation in Euclidean spaces of the perturbed unit eigenvectors corresponding to a simple eigenvalue, Topol. Methods Nonlinear Anal. 55 (2020), 169--184. DOI: 10.12775/TMNA.2019.093.

Benevieri P. - Calamai A. - Furi M. - Pera M.P., Global continuation of the eigenvalues of a perturbed linear operator, Ann. Mat. Pura Appl. (4) 197 (2018), no. 4, 1131--1149.

Benevieri P. - Calamai A. - Furi M. - Pera M.P., On General Properties of n-th order Retarded Functional Differential Equations, Rend. Istit. Mat. Univ. Trieste 49 (2017), 73--93.

Benevieri P. - Calamai A. - Furi M. - Pera M.P., On the persistence of the eigenvalues of a perturbed Fredholm operator of index zero under nonsmooth perturbations, Z. Anal. Anwendungen, 36 (2017), 99--128. doi: 10.4171/ZAA/1581.

Benevieri P. - Calamai A. - Furi M., On the degree for oriented quasi-Fredholm maps: its uniqueness and its effective extension of the Leray--Schauder degree, Topological Methods in Nonlinear Analysis 46 (2015), no. 1, 401--430.

Benevieri P. - Calamai A. - Furi M. - Pera M.P., Global continuation of forced oscillations of retarded functional motion equations on manifolds, J. Fixed Point Theory Appl. 16 (2014), 273-300, doi: 10.1007/s11784-015-0215-6.

Chiappinelli R. - Furi M. - Pera M.P., Topological Persistence of the Unit Eigenvectors of a Perturbed Fredholm Operator of Index Zero , Z. Anal. Anwendungen 33 (2014), no. 3, 347-367.

Benevieri P. - Calamai A. - Furi M. - Pera M.P., Global Continuation of Periodic Solutions for Retarded Functional Differential Equations on Manifolds, Special Issue titled "Jean Mawhin's achievements in Nonlinear Analysis", Boundary Value Problems 2013, 2013:21, doi: 10.1186/1687-2770-2013-21.

Chiappinelli R. - Furi M. - Pera M.P., Persistence of the normalized eigenvectors of a perturbed operator in the variational case, Glasgow Mathematical Journal Trust 2013 (doi:10.1017/S0017089512000791).

Benevieri P. - Calamai A. - Furi M. - Pera M.P., On the Existence of Forced Oscillations of Retarded Functional Motion Equations on a Class of Topologically Nontrivial Manifolds, Rend. Istit. Mat. Univ. di Trieste 44 (2012), 5--17.

Benevieri P. - Calamai A. - Furi M. - Pera M.P., On General Properties of Retarded Functional Differential Equations on Manifolds, Discrete Cont. Dynam. Systems 33 (2013), no. 1, 27--46.

Benevieri P. - Calamai A. - Furi M. - Pera M.P., A Continuation Result for Forced Oscillations of Constrained Motion problems with Infinite Delay, Advanced Nonlinear Studies  13 (2013), 263--278.

Furi M. - Martelli M. - Vignoli A., Longitudinal librations of a satellite, Electronic J. Differential Equations, Vol. 2011 (2011), no. 134, 1--15.

Chiappinelli R. - Furi M. - Pera M.P., A new theme in nonlinear analysis: continuation and bifurcation of the unit eigenvectors of a perturbed linear operator, Communications in Applied Analysis 15 (2011), no. 2, 3 and 4, 299--312.

Furi M. - Pera M.P. - Spadini M., Periodic solutions of retarded functional perturbations of autonomous differential equations on manifolds, Communications in Applied Analysis 15 (2011), no. 2, 3 and 4, 381--394.

Benevieri P. - Furi M., On the uniqueness of the degree for nonlinear Fredholm maps of index zero between Banach manifolds, Communications in Applied Analysis 15 (2011), no. 2, 3 and 4, 203--216.

Benevieri P. - Calamai A. - Furi M. - Pera M.P., On the existence of forced oscillations for the spherical pendulum acted on by a retarded periodic force, Journal of Dynamics and Differential Equations 23 (2011), no. 3, 541--549 (doi: 10.1007/s10884-010-9201-2).

Furi M. - Pera M.P. - Spadini M., A set of axioms for the degree of tangent vector fields on differentiable manifolds, Fixed Point Theory and Applications, Volume 2010, Article ID 845631, 11 pages, 2010 (doi:10.1155/2010/845631).

Chiappinelli R. - Furi M. - Pera M.P., Topological Persistence of the Normalized Eigenvectors of a Perturbed Selfadjoint Operator, Applied Mathematics Letters 23 (2010), 193--197.

Calamai A. - Furi M. - Vignoli A., An overview on spectral theory for nonlinear operators, Communications in Applied Analysis  13 (2009), no. 4, 509--534.

Furi M. - Landsberg A.S. - Martelli M., On the longitudinal librations of Hyperion, J. Fixed Point Theory Appl. 5 (2009), no. 2, 249--264.

Benevieri P. - Calamai A. - Furi M. - Pera M.P., Fast Forced Oscillations for Constrained Motion problems with Delay, Communications in Applied Analysis  13 (2009), no. 4, 497--508.

Furi M. - Spadini M., Periodic perturbations with delay of autonomous differential equations on manifolds, Advanced Nonlinear Studies 9 (2009), no. 2, 263--276.

Benevieri P. - Calamai A. - Furi M. - Pera M.P., On Forced Fast Oscillations for Delay Differential Equations on Compact Manifolds, J. Differential Equations 246 (2009), no. 4, 1354--1362.

Furi M. - Martelli M. - O'Neill M., Global Stability of Equilibria, J. Difference Equ. Appl. 15 (2009), no. 4, 387--397.

Benevieri P. - Calamai A. - Furi M. - Pera M.P., Delay differential equations on manifolds and applications to motion problems for forced constrained systems, Z. Anal. Anwendungen 28 (2009), no. 4, 451--474.

Benevieri P. - Calamai A. - Furi M. - Pera M.P., Retarded functional differential equations on manifolds and applications to motion problems for forced constrained systems, Advanced Nonlinear Studies 9 (2009), no. 1, 199--214.

Furi M. - Martelli M. - Pera M.P., Bifurcation of Fixed Points from a Manifold of Trivial Fixed Points in the Infinite Dimensional Case, J. Fixed Point Theory Appl. 2 (2007), no. 2, 293--312.

Chiappinelli R. - Furi M. - Pera M.P., Normalized Eigenvectors of a Perturbed Linear Operator via General Bifurcation, Glasgow Mathematical Journal 50 (2008), no. 2, 303--318.

Calamai A. - Furi M. - Vignoli A., A new spectrum for continuous nonlinear operators in Banach spaces, Nonlinear Funct. Anal. Appl., 14 (2009), no. 2, 317-347.

Benevieri P. - Calamai A. - Furi M. - Pera M.P., Forced oscillations for delay motion equations on manifolds, Electronic J. Differential Equations 2007, no. 62, 5 pp. (electronic).

Benevieri P. - Calamai A. - Furi M. - Pera M.P., Global branches of periodic solutions for forced delay differential equations on compact manifolds, J. Differential Equations 233 (2007), no. 2, 404--416.

Benevieri P. - Calamai A. - Furi M., A degree theory for a class of perturbed Fredholm maps II, Fixed Point Theory and Applications 2006, Art. ID 27154, 20 pp.

Furi M. - Pera M.P., Bifurcation of fixed points from a manifold of trivial fixed points, Nonlinear Funct. Anal. Appl. 11 (2006), no. 2, 265--292.

Benevieri P. - Calamai A. - Furi M., A degree theory for a class of perturbed Fredholm maps, Fixed Point Theory and Applications 2005, no. 2, 185--206.

Furi M. - Landsberg A.S. - Martelli M., On the chaotic behaviour of the satellite Hyperion, American Mathematical Society Special Session on Difference Equations and Discrete Dynamics, J. Difference Equ. Appl. 11 (2005), no. 7, 635--643.

Furi M. - Pera M.P. - Spadini M., On the uniqueness of the fixed point index on differentiable manifolds, Fixed Point Theory and Applications 2004, no. 4, 251--259.

Furi M. - Pera M.P. - Spadini M., The fixed point index of the Poincaré translation operator on manifolds, "Handbook of Topological Fixed Point Theory", Brown R.F., Furi M., Górniewicz L., Jiang B. Eds., 741--782, Springer, Dordrecht, 2005.

Benevieri P. - Furi M. - Martelli M. - Pera M.P., Atypical bifurcation without compactness, Z. Anal. Anwendungen 24 (2005), no. 1, 137--147.

Benevieri P. - Furi M., A degree theory for locally compact perturbations of Fredholm maps in Banach spaces, Abstract and Applied Analysis 2006, Art. ID 64764, 20 pp.

Furi M. - Martelli M. - O'Neill M. - Staples C., Chaotic orbits of a pendulum with variable length, Electronic J. Differential Equations 2004, no. 36, 14 pp. (electronic).

Benevieri P. - Furi M. - Pera M.P. - Spadini M., About the sign of oriented Fredholm operators between Banach spaces, Z. Anal. Anwendungen 22 (2003), no. 3, 619--645.

Furi M. - Vignoli A., An extension of the notion of zero-epi maps to the context of topological spaces, Z. Anal. Anwendungen 21 (2002), no. 2, 485--493.

Furi M., Stably solvable maps are unstable under small perturbations, Z. Anal. Anwendungen 21 (2002), no. 1, 203--208.

Furi M. - Pera M.P. - Spadini M., Multiplicity of forced oscillations for scalar differential equations, Electronic J. Differential Equations 2001, no. 36, 9 pp. (electronic).

Furi M. - Pera M.P. - Spadini M., Multiplicity of forced oscillations on manifolds and applications to motion problems with one-dimensional constraints, Wellposedness in optimization and related topics (Gargnano, 1999), Set-Valued Analysis 9 (2001), no. 1-2, 67--73.

Benevieri P. - Furi M., Bifurcation results for families of Fredholm maps of index zero between Banach spaces, Nonlinear analysis and its applications (St. John's, NF, 1999), Nonlinear Analysis Forum 6 (2001), no. 1, 35--47.

Benevieri P. - Furi M., On the concept of orientability for Fredholm maps between real Banach manifolds, Topol. Methods in Nonlinear Anal. 16 (2000), no. 2, 279--306.

Benevieri P. - Furi M. - Pera M.P., On the Product Formula for the Oriented Degree for Fredholm Maps of Index Zero between Banach Manifolds, Nonlinear Anal. 48 (2002), no. 6, Ser. A: Theory Methods, 853--867.

Benevieri P. - Furi M. - Pera M.P., The Invariance of Domain for C1 Fredholm Maps of index zero, in "Progress in Nonlinear Differential Equations and Their Applications", Jürgen Appell editor, Vol. 40, Birkhäuser Verlag, Basel, 2000, 35--39.

Furi M. - Pera M.P. - Spadini M., Forced oscillations on manifolds and multiplicity results for periodically perturbed autonomous systems, Journal of Computational and Applied Mathematics 113 (2000), 241--254.

Cecchi M. - Furi M. - Marini M. - Pera M.P., Fredholm Linear Operators Associated with Ordinary Differential Equations on Noncompact Intervals, Electronic J. Differential Equations 1999, no. 44, 16 pp. (electronic).

Furi M. - Spadini M., Branches of forced oscillations for periodically perturbed second order autonomous ODE's on manifolds, J. Differential Equations 154 (1999), no. 1, 96--106.

Benevieri P. - Furi M., A simple notion of orientability for Fredholm maps of index zero between Banach manifolds and degree theory, Dedicated to the memory of Gilles Fournier (Sherbrooke, PQ, 1997), Ann. Sci. Math. Québec 22, (1998), no. 2, 131--148.

Furi M. - Spadini M., Multiplicity of forced oscillations for the spherical pendulum, Topol. Methods Nonlinear Anal. 11 (1998), no. 1, 147--157.

Furi M. - Pera M.P., Carathéodory Periodic Perturbations of the Zero Vector Field on Manifolds, Topol. Methods Nonlinear Anal. 10 (1997), no. 1, 79--92.

Furi M. - Spadini M., On the set of harmonic solutions of periodically perturbed autonomous differential equations on manifolds, Nonlinear Anal. 29 (1997), no. 8, 963--970.

Edelson A.L. - Furi M., Global Solution Branches for Semilinear Equations in R^n, Nonlinear Anal. 9 (1997), no. 9, 1521--1532.

Furi M. - Pera M.P., Remarks on global branches of harmonic solutions to periodic ODE's on manifolds, Boll. Un. Mat. Ital. A (7) 11 (1997), no. 3, 709--722.

Furi M. - Pera M.P., Global Bifurcation of Fixed Points and the Poincaré Translation Operator on Manifolds, Ann. Mat. Pura Appl. (4) 173 (1997), 313--331.

Furi M. - Spadini M., On the fixed point index of the flow and applications to periodic solutions of differential equations on manifolds, Boll. Un. Mat. Ital. A (7) 10 (1996), no. 2, 333--346.

Furi M., Second order differential equations on manifolds and forced oscillations, Proceedings of the Séminaire de Mathématiques Supérieures on "Topological Methods in Differential Equations and Inclusions" (Montréal, PQ, July 11-22, 1994), Granas A. and Frigon M. Editors, NATO ASI Series C, Vol. 472, Kluwer Academic Publishers, Dordrecht NL, 1995, 89--127.

Furi M. - Martelli M. - Pera M.P., General Bifurcation Theory: Local Results and Applications, in "Differential Equations and Applications to Biology and to Industry" (Claremont, CA, 1994), Cooke K. - Cumberbatch E. - Martelli M. - Tang B. - Thieme H. Editors, 101--115, World Sci. Publ., River Edge, NJ, 1996.

Furi M. - Martelli M., A multi-dimensional version of Rolle's Theorem, Amer. Math. Monthly 102 (1995), no. 2, 243--249.

Furi M. - Martelli M., Strictly Increasing Differentiable Functions, The College Mathematics Journal, 2 (1994), 125--127.

Furi M. - Pera M.P., On the notion of winding number for closed curves and applications to forced oscillations on even dimensional spheres, Boll. Un. Mat. Ital. A (7) 7 (1993), no. 3, 397--407.

Furi M. - Pera M.P., A continuation principle for periodic solutions of forced motion equations on manifolds and applications to bifurcation theory, Pacific J. Math. 160 (1993), no. 2, 219--244.

Furi M. - Martelli M., On the mean Value Theorem, Inequality and Inclusion, Amer. Math. Monthly 98 (1991), no. 9, 840--846.

Furi M. - Pera M.P., The forced spherical pendulum does have forced oscillations, in "Delay Differential Equations and Dynamical Systems" (Claremont, CA, 1990), Busenberg S. and Martelli M. editors, 176--182, Lecture Notes in Math. 1475, Springer, Berlin, 1991.

Furi M. - Pera M.P., A continuation principle for the forced spherical pendulum, in "Fixed Point Theory and Applications" (Marseille, 1989), Théra M.A. and Baillon J.-B. editors, 141--154, Pitman Res. Notes Math. Ser., 252, Longman Sci. Tech., Harlow, 1991.

Furi M. - Pera M.P., On the existence of forced oscillations for the spherical pendulum, Boll. Un. Mat. Ital. B (7) 4 (1990), no. 2, 381--390.

Furi M., A note on maps sending open sets into open sets, Boll. Un. Mat. Ital. B (7) 4 (1990), no. 2, 423--427.

Furi M. - Pera M.P., Illustrazione del principio di continuazione in dimensione finita tramite il computer e metodi numerici per la risoluzione di sistemi non lineari di n equazioni in n incognite, Seminari dell'Ist. Mat. U. Dini, 1987.

Cecchi M. - Furi M. - Marini M., About asymptotic problems for ordinary differential equations, Boll. Un. Mat. Ital. B (7) 2 (1988), no. 2, 333--343.

Furi M. - Pera M.P., On the fixed point index in locally convex spaces, Proc. Roy. Soc. Edinburgh Sect. A 106 (1987), no. 1-2, 161--168.

Cecchi M. - Furi M. - Marini M., About the solvability of ordinary differential equations with asymptotic boundary conditions, Boll. Un. Mat. Ital. C (6) 4 (1985), no. 1, 329--345.

Furi M. - Pera M.P., A continuation method on locally convex spaces and applications to ordinary differential equations on noncompact intervals, Ann. Polon. Math. 47 (1987), no. 3, 331--346.

Furi M. - Pera M.P., A continuation principle for forced oscillations on differentiable manifolds, Pacific J. of Math. 121 (1986), no. 2, 321--338.

Furi M. - Pera M.P., Global branches of periodic solutions for forced differential equations on nonzero Euler characteristic manifolds, Boll. Un. Mat. Ital., Anal. Funz. e Appl. C (6) 3 (1984), no. 1, 157--170.

Cecchi M. - Furi M. - Marini M., On continuity and compactness of some nonlinear operators associated with differential equations in noncompact intervals, Nonlinear Anal. 9 (1985), no. 2, 171--180.

Furi M. - Nistri P. - Pera M.P. - Zezza P.L., Topological methods for the global controllability of nonlinear systems, J. Optim. Theory Appl. 45 (1985), no. 2, 231--256.

Furi M. - Nistri P. - Pera M.P. - Zezza P.L., Linear controllability by piecewise constant controls with assigned switching time, J. Optim. Theory and Appl. 45 (1985), no. 2, 219--229.

Furi M., Sul concetto di biforcazione atipica, Rend. Seminario Matematico e Fisico di Milano, Vol. LIII, 1983, 75--81.

Furi M. - Pera M.P., Co-bifurcating branches of solutions for nonlinear eigenvalue problems in Banach spaces, Ann. Mat. Pura Appl. (4) 135 (1983), 119--131.

Furi M. - Pera M.P., Nonbifurcating branches of forced oscillations for the differential system x'(t) = \lambda f(t,x(t)), \lambda≥0, Boll. Un. Mat. Ital. C (6) 2 (1983), no. 1, 187--194.

Furi M. - Pera M.P. - Vignoli A., Components of positive solutions for non-linear equations with several parameters, Boll. Un. Mat. Ital., Anal. Funz. e Appl. C (6) 1 (1982), no. 1, 285--302.

Furi M. - Vignoli A., Unbounded nontrivial branches of eigenfunctions for nonlinear equations, Nonlinear Anal. 6 (1982), no. 11, 1267--1270.

Furi M. - Pera M.P., On unbounded branches of solutions for nonlinear operator equations in the nonbifurcating case, Boll. Un. Mat. Ital. B (6) 1 (1982), no. 3, 919--930.

Furi M. - Pera M.P., An elementary approach to boundary value problems at resonance, Nonlinear Anal. 4 (1980), no. 6, 1081--1089.

Furi M. - Pera M.P., On the existence of an unbounded connected set of solutions for nonlinear equations in Banach spaces, Atti Accad. Naz. Lincei Rend. Cl. Sci. Fis. Mat. Natur. (8) 67 (1979), no. 1-2, 31--38.

Furi M. - Martelli M. - Vignoli A., On the solvability of nonlinear operator equations in normed spaces, Ann. Mat. Pura. (4) 124 (1980), 321--343.

Furi M. - Martelli M. - Vignoli A., Contributions to the spectral theory for nonlinear operators in Banach spaces, Ann. Mat. Pura Appl. (4) 118 (1978), 229--294. 

Furi M. - Martelli M. - Vignoli A., Stably-solvable operators in Banach spaces, Atti Accad. Naz. Lincei Rend. Cl. Sci. Fis. Mat. Natur. (8) 60 (1976), no. 1, 21--26.

Furi M. - Vignoli A., Spectrum for nonlinear maps and bifurcation in the non differentiable case, Ann. Mat. Pura Appl. (4) 113 (1977), 265--285. 

Furi M. - Vignoli A., On surjectivity for nonlinear maps in Banach spaces, Ann. Mat. Pura Appl. (4) 112 (1977), 205--216. 

Furi M. - Vignoli A., A nonlinear spectral approach to surjectivity in Banach spaces, J. Functional Analysis 20 (1975), no. 4, 304--318.

Furi M. - Martelli M., On the minimal displacement under acyclic-valued maps defined on a class of ANR's, Boll. Un. Mat. Ital. (4) 11 (1975), no. 3, 238--246.

Furi M. - Martelli M., On alpha-Lipschitz retractions of the unit closed ball onto its boundary, Atti Accad. Naz. Lincei Rend. Cl. Sci. Fis. Mat. Natur. (8) 57 (1974), no. 1-2, 1974, 61--65.

Furi M. - Martelli M., A degree for a class of acyclic-valued vector fields in Banach spaces, Ann. Scuola Norm. Sup. Pisa Cl. Sci. (4) I (1974), no. 3-4, 301--310.

Furi M. - Martelli M., A Lefschetz type theorem for the minimal displacement of points under maps defined on a class of ANR's, Boll. Un. Mat. Ital. (4) 10 (1974), 174--181.

Furi M. - Martelli M., On the minimal displacement of points under alpha-Lipschitz maps in normed spaces, Boll. Un. Mat. Ital. (4) 9 (1974), 791--799.

Furi M. - Franchetti C., Periodic solutions for the equation x"+f(x)x'2+g(x)=0, Boll. Un. Mat. Ital. (4) 8 (1973), 509--517.

Furi M. - Franchetti C., Some characteristic properties of real Hilbert spaces, Revue Roumaine Math. Pures Appl. 17 (1972), no. 7, 1045--1048.

Furi M. - Martelli M., Some fixed-point theorems for multi-valued mappings in topological vector spaces, Ann. Mat. Pura Appl. (4) 92 (1972), 169--175. 

Furi M. - Martelli M., A characterization of compact filterbasis in complete metric spaces, Rend. Ist. Mat. Univ. Trieste 2 (1970), no. 2, 109--113.

Furi M. - Martelli M. - Vignoli A., On minimum problems for families of functionals, Ann. Mat. Pura ed Appl. (4) 86 (1970), 181--187.

Furi M. - Vignoli A., A remark about some fixed point theorems, Boll. Un. Mat. Ital. (4) 3 (1970), 197--200.

Furi M. - Vignoli A., On a property of the unit sphere in a linear normed space, Bull. Acad. Polon. Sci. Sér. Sci. Math. Astronom. Phys. 18 (1970), 333--334.

Furi M. - Vignoli A., On alpha-nonexpansive mappings and fixed points, Atti Accad. Naz. Lincei Rend. Cl. Sci. Fis. Mat. Natur. (8) 48 (1970), no. 2, 195--198.

Furi M. - Vignoli A., A characterization of well-posed minimum problems in a complete metric space, J. Optimization Theory Appl. 5 (1970), 452--461.

Furi M. - Vignoli A., About well-posed optimization problems for functionals in metric spaces, J. Optimozation Theory Appl.5 (1970), no. 3, 223--229.

Furi M. - Vignoli A., Fixed points for densifying mappings, Atti Accad. Naz. Lincei Rend. Cl. Sci. Fis. Mat. Natur. (8) 47 (1970), no. 6, 465--467.

Furi M. - Martelli M., Successioni di trasformazioni in uno spazio metrico e punti fissi, Atti Accad. Naz. Lincei Rend. Cl. Sci. Fis. Mat. Natur. (8) 47 (1969), no. 1-2, 1969, 27--31.

Furi M. - Vignoli A., A fixed point theorem in complete metric spaces, Boll. Un. Mat. Ital. (4) 2 (1969), 505--509.

Furi M. - Vignoli A., On the regularization of a nonlinear ill-posed problem in Banach spaces, J. Optimozation Theory Appl. 4 (1969), no. 3, 206--209.

Furi M., Un teorema di punto fisso per trasformazioni di uno spazio metrico completo in sé, Atti Accad. Naz. Lincei Rend. Cl. Sci. Fis. Mat. Natur. (8) 45 (1968), no. 5, 1968, 207--211.

Furi M., Un criterio di limitatezza per una classe di equazioni differenziali del secondo ordine, Boll. Un. Mat. Ital., (4) 1 (1968), 585--590.