[1]  M. R. Grossinho, R. Martins, Subharmonic oscillations for some second-order differential equations   without Landsman-Lazer conditions, Proceedings of the International Conference Dynamical Systems and Differential Equations, May 2000, Atlanta, published as an added volume of Discrete and Continuous Dynamical Systems. 

[2]  R. Martins, Existence of  periodic solutions for second-order differential equations with singularities and the strong force condition, J. Math. Anal. Appl., Volume 317, Issue 1, 1 May 2006, 1-13. 

[3]  R. Martins, Soluções subharmonicas de alguns problemas não lineares, Master thesis. 2000. 

[4]  J. Campos, A. Margheri, R. Martins, C. Rebelo, A note on a modified version of the Poincaré-Birkhoff theorem, J. Differential Equations, Volume 203, Issue 1, 15 August 2004, 55-63.

[5]  R. Martins, The effect of inversely unstable solutions on the attractor of the forced pendulum equation with friction, J. Differential Equations, Volume 212, Issue 2, 15 May 2005, 351-365.

[6]  R. Martins, One-dimensional attractor for a dissipative system with a cylindrical phase space, Discrete and Continuous Dynamical Systems-Series A, Volume 14, Issue 3, March 2005, 533-547.

[7]  R. Martins, Dinâmica de sistemas forçados e dissipativos com uma coordenada angular, PhD thesis, 2005. 

[8]  R. Martins, The attractor of an equation of Tricomi's type, Accepted for publication on J. Math. Anal. Applications.

[9]  R. Martins, A. Ureña, The necessity of the star-shaped condition on Ding's version of the Poincaré-Birkhoff theorem, Bull. Lond. Math. Soc. 39, No. 5, 2007, 803-810.

[10] M. Guerra, R. Pinto, R. Martins,  J. P. Casquilho, On the effect of a rotating magnetic field or sample on the bend Freedericksz critical field in nematic slabs, Molecular Crystals and Liquid Crystals. 508, 337-347 (2009). 

[11] A. Margheri, R. Martins, Generalized synchronization in non-autonomous linearly coupled systems, Journal of Differential Equations. 249, 3215-3232 (2010).

[12] J. P. Casquilho, R. Martins, On the stability of shear flows in nematics, Theoretical and Computational Fluid Dynamics, Volume 26, Issue 1, 381-389 (2012).

[13] R. Martins, G. Morais, Generalized synchronization in a system of several non-autonomous oscillators coupled by a médium, Kybernetika, Vol. 51 (2015), issue 2, pp. 347-373.

[14] R. Martins, Why are we not able to see beyond three dimensions?, Mathematical Intelligencer, Volume 38, Issue 4, pp 46-51 (2016).

[15] R. Martins, Maths on TV? Yes, we can!, Bridges 2016 Conference Proceedings, Edited by Eve Torrence, Bruce Torrence, Carlo H. Séquin, Douglas McKenna, Kristóf Fenyvesi, and Reza Sarhangi, 2016, pp 565-566.

[16] R. Martins, The (not so simple!) chain fountain (2017), Experimental Mathematics, DOI: 10.1080/10586458.2017.1413454