T. Li, J. Llibre.
Limit cycles of piecewise polynomial differential systems with the discontinuity line xy=0.
Commun. Pure Appl. Anal., 20(11), 3871-3893. 2021. [DOI]
PreprintAbstractPreprint at DDDUAB

T. Li, J. Llibre.
Phase portraits of separable quadratic systems and a bibliographical survey on quadratic systems.
Exposition. Math., 39, 540-565. 2021. [DOI]
PreprintAbstractPreprint at DDDUAB

J. Llibre.
Central configurations of the circular restricted 4-body problem with three equal primaries in the collinear central configuration of the 3-body problem.
Trends in Computer Science and Information Technology, 6(1), 1-6. 2021. [DOI]
PreprintAbstractPreprint at DDDUAB

J. Llibre.
Integrability and limit cycles via first integrals.
Symmetry (Basel), 13(9), 1-21. 2021. [DOI]
AbstractFull PDFPreprint at DDDUAB

J. Llibre, J. R. Moraes.
Limit cycles of 3-dimensional discontinuous piecewise differential systems formed by linear centers.
Sao Paulo J. Math. Sci., 15(2), 858-874. 2021. [DOI]
PreprintAbstractPreprint at DDDUAB

J. Llibre, B. D. Lopes, P. R. Silva.
Bifurcations of the Riccati quadratic polynomial differential system.
Internat. J. Bifur. Chaos Appl. Sci. Engrg., 31(6), 2150094:1-13. 2021. [DOI]
PreprintAbstractPreprint at DDDUAB

J. Llibre, L. d. A. S. Menezes.
The Markus–Yamabe conjecture does not hold for piecewise discontinuous linear differential systems separated by one straight line.
J. Dyn. Diff. Equat., 33, 659-676. 2021. [DOI]
PreprintAbstractPreprint at DDDUAB

J. Llibre, M. Messias, A. C. Reinol.
Global dynamics and bifurcation of periodic orbits in a modified Nosé-Hoover oscillator.
J. Dyn. Control Syst., 27, 491-506. 2021. [DOI]
PreprintAbstractPreprint at DDDUAB

J. Llibre, A. Murza.
Polynomial vector fields on the Clifford torus.
Internat. J. Bifur. Chaos Appl. Sci. Engrg., 31(4), 2150057:1-5. 2021. [DOI]
PreprintAbstractPreprint at DDDUAB

J. Llibre, R. D. S. Oliveira, C. A. B. Rodrigues.
Quadratic systems with an invariant algebraic curve of degree 3 and a Darboux invariant.
Electron. J. Differential Equations, 2021(69), 1-52. 2021.
PreprintAbstractPreprint at DDDUAB

J. Llibre, R. D. S. Oliveira, Y. Zhao.
On the birth and death of algebraic limit cycles in quadratic differential systems.
European J. Appl. Math., 32, 317-336. 2021. [DOI]
PreprintAbstractPreprint at DDDUAB

J. Llibre, D. Pasca, C. Valls.
The circular restricted 4-body problem with three equal primaries in the collinear central configuration of the 3-body problem.
Celestial Mech. Dynam. Astronom., 133(53), 1-13. 2021. [DOI]
PreprintAbstractPreprint at DDDUAB

J. Llibre, C. Pessoa, J. D. Ribeiro.
Rational first integrals of the Liénard equations: The solution to the Poincaré problem for the Liénard equations.
An. Acad. Brasil. Ci., 93(4), 1-7. 2021. [DOI]
PreprintAbstractPreprint at DDDUAB

J. Llibre, R. O. Ramírez, V. Ramírez.
Complete integrability of vector fields in $R^N$.
J. Geom. Phys., 168, 104308:1-25. 2021. [DOI]
PreprintAbstractPreprint at DDDUAB

J. Llibre, R. O. Ramírez, V. Ramírez.
The center problem for the class of $\lambda$-$\Omega$ differential systems.
Rend. Circ. Mat. Palermo (2), 70, 1483-1499. 2021. [DOI]
PreprintAbstractPreprint at DDDUAB

J. Llibre, A. Sá.
Minimal set of periods for continuous self-maps of the eight space.
Fixed Point Theory Algorithms Sci. Eng., 2021(3), 1-26. 2021. [DOI]
PreprintAbstractPreprint at DDDUAB

J. Llibre, T. Saeed, E. E. Zotos.
Periodic orbits and equilibria for a seventh-order generalized Hénon-Heiles Hamiltonian system.
J. Geom. Phys., 167, 104290:1-12. 2021. [DOI]
PreprintAbstractPreprint at DDDUAB

J. Llibre, T. Salhi.
On a class of polynomial differential systems of degree 4: phase portraits and limit cycles.
Topol. Methods Nonlinear Anal., 57(1), 441-463. 2021. [DOI]
PreprintAbstractPreprint at DDDUAB

J. Llibre, V. F. Sirvent.
Entropy and periods for continuous graph maps.
Comput. Appl. Math., 40, 300:1-11. 2021. [DOI]
PreprintAbstractPreprint at DDDUAB

J. Llibre, V. F. Sirvent.
Periodic structure of the transversal maps on surfaces.
J. Fixed Point Theory Appl., 23(74), 1-13. 2021. [DOI]
PreprintAbstractPreprint at DDDUAB