Klun G, Fonda A, Sfecci A. On Dini derivatives of real functions.; 2021.

Fonda A, Klun G, Sfecci A. Non-well-ordered lower and upper solutions for semilinear systems of PDEs. Communications in Contemporary MathematicsCommunications in Contemporary Mathematics [Internet]. 2021  :2150080. Available from: https://doi.org/10.1142/S0219199721500802

Fonda A, Klun G, Sfecci A. Periodic Solutions of Second-Order Differential Equations in Hilbert Spaces.  [Internet]. 2021  ;18(5):223. Available from: https://doi.org/10.1007/s00009-021-01857-8

Fonda A, Klun G, Sfecci A. Well-Ordered and Non-Well-Ordered Lower and Upper Solutions for Periodic Planar Systems. Advanced Nonlinear Studies [Internet]. 2021  ;21(2):397 - 419. Available from: https://doi.org/10.1515/ans-2021-2117

Klun G. On functions having coincident p-norms. Annali di Matematica Pura ed Applicata (1923 -) [Internet]. 2020  ;199:955-968. Available from: https://doi.org/10.1007/s10231-019-00907-z

Fonda A, Klun G, Sfecci A. Periodic solutions of nearly integrable Hamiltonian systems bifurcating from infinite-dimensional tori. NONLINEAR ANALYSIS [Internet]. 2020  . Available from: https://doi.org/10.1016/j.na.2019.111720

Fonda A, Klun G. On the topological degree of planar maps avoiding normal cones. TOPOLOGICAL METHODS IN NONLINEAR ANALYSIS [Internet]. 2019  ;53:825-845. Available from: http://dx.doi.org/10.12775/TMNA.2019.034

Klun G. Gli abachi: antichi strumenti precursori delle moderne macchine da calcolo.  [Internet]. 2015  . Available from: http://hdl.handle.net/10077/10884