- O.
**Ragos**and C. Zagouras : "The zero velocity surfaces in the photogravitational restricted three-body problem",

1988,*Earth, Moon, and Planets*,**41**, pp.257-278. -
O.

**Ragos**and C. Zagouras : "Periodic solutions about the `out of plane' equilibrium points in the photogravitational restricted three-body problem",

1988,*Celestial Mechanics*,**44**, pp.135-154. -
O.

**Ragos**, C.G. Zagouras and E. Perdios : "Periodic motion around stable collinear equilibrium point in the photogravitational restricted problem of three bodies",

1991,*Astrophysics and Space Science*,**182**, pp.313-336. -
O.

**Ragos**and C. Zagouras : "Periodic solutions around the collinear Lagrangian points in the photogravitational restricted three-body problem : Sun-Jupiter case",

1991,*Celestial Mechanics*,**50**, pp.325-347. -
E. Perdios, C.G. Zagouras and O.

**Ragos**: "Three-dimensional bifurcations of periodic solutions around the triangular equilibrium points of the restricted three-body problem",

1991,*Celestial Mechanics and Dynamical Astronomy*,**51**, pp.349-362. -
O.

**Ragos**and C.G. Zagouras : "On the existence of the `out of plane' equilibrium points in the the photogravitational restricted three-body problem",

1993,*Astrophysics and Space Science*,**209**, pp.267-271. -
O.

**Ragos**and F.A. Zafiropoulos : "A numerical study of the influence of the Poynting-Robertson effect on the equilibrium points of the photogravitational restricted three-body problem : I. Coplanar case",

1995,*Astronony and Astrophysics*,**300**, pp.568-578. -
O.

**Ragos**and F.A. Zafiropoulos and M.N. Vrahatis : "A numerical study of the influence of the Poynting-Robertson effect on the equilibrium points of the photogravitational restricted three-body problem : II. Out of plane case",

1995,*Astronony and Astrophysics*,**300,**pp.579-590. -
M.N. Vrahatis, O.

**Ragos**, T. Skiniotis, F.A. Zafiropoulos and T.N. Grapsa : "RFSFNS: A portable package for the numerical determination of the number and the calculation of roots of Bessel functions",

1995,*Computer Physics Communications*,**92**, pp.252-266. -
L. Drossos, O.

**Ragos**, M.N. Vrahatis and T. Bountis : "Method for computing long periodic orbits of dynamical systems",

1995,*Physical Review E*,**53(1)**, pp.1206-1211. -
M.N. Vrahatis, O.

**Ragos**, F.A. Zafiropoulos and T.N. Grapsa : "Locating and computing zeros of Airy functions",

1996,*Zeitschrift fur Angewandte Mathematik und Mechanik*,**76**, pp.419-422. -
M.N. Vrahatis, T.N. Grapsa, O.

**Ragos**and F.A. Zafiropoulos : "On the localization and computation of zeros of Bessel functions",

1996,*Zeitschrift fur Angewandte Mathematik und Mechanik*,**77(6)**, pp.467-475. -
C.G. Zagouras, E.Perdios and O.

**Ragos**: "New kinds of asymmetric periodic orbits in the restriced three-body problem",

1996,*Astrophysics and Space Science*,**240**, pp.273-293. -
M.N. Vrahatis, O.

**Ragos**, T. Skiniotis, F.A. Zafiropoulos and T.N. Grapsa : "The topological degree theory for the localization and computation of complex zeros of Bessel functions",

1996,*Numerical Functional Analysis and Optimization*,**18(1&2)**, pp.227-234. -
O.

**Ragos**, K.E. Papadakis and C.G. Zagouras : "Stability regions and quasi-periodic motion in the vicinity of triangular equilibrium points",

1997,*Celestial Mechanics and Dynamical Astronomy*,**67**, pp.251-274. -
P. Kravanja, O.

**Ragos**, M.N. Vrahatis, and F.A. Zafiropoulos : "ZEBEC: A mathematical software package for computing zeros of Bessel functions of real order and complex argument",

1998,*Computer Physics Communications*,**113**, pp.220-238. -
P. Kravanja, M. Van Barel, O.

**Ragos**, M.N. Vrahatis, and F.A. Zafiropoulos : "ZEAL: A mathematical software package for computing zeros of analytic functions",

2000,*Computer Physics Communications*,**124**, pp.212-232. -
V.S. Kalantonis, E.A. Perdios, A.E. Perdiou, O.

**Ragos**, and M.N. Vrahatis : "On the application of optimization methods to the determination of members of families of periodic solutions",

2003,*Astrophysics and Space Science*,**288(4)**, pp.581-590. -
V.S. Kalantonis, E.A. Perdios, A.E. Perdiou, O.

**Ragos**, and M.N. Vrahatis : "Deflation techniques for the determination of periodic solutions of a certain period",

2003,*Astrophysics and Space Science*,**288(4)**, pp.591-599. -
E.A. Perdios and O.

**Ragos**: "Asymptotic and periodic motion around collinear equilibria in the Chermnykh's problem",

2004,*Astronomy and Astrophysics*,**414**, pp.361-371. -
V.S. Kalantonis, E.A. Perdios and O.

**Ragos**: "Asymptotic and periodic motion around L_3 in the photogravitational restricted three-body problem",

2006,*Astrophysics and Space Science*,**301(1)**, pp.157-165. -
K. Papadakis, O.

**Ragos**and C. Litzerinos, : "Asymmetric periodic orbits in the photogravitational Copenhagen problem",

2009,*Journal of Computational and Applied Mathematics*,**227**, pp.102-114. -
I. Haranas and O.

**Ragos**: "Yukawa-type potential effects in satellite dynamics",

2011,*Astrophysics and Space Science*,**331(1)**, pp.115-119. -
I. Haranas, O.

**Ragos**and V. Mioc : "Yukawa-type potential effects in the anomalistic period of celestial bodies",

2011,*Astrophysics and Space Science*,**332(1)**, pp.107-113. -
I. Haranas and O.

**Ragos**: "Calculation of radar signal delays in the vicinity of the Sun due to the contribution of a Yukawa correction term in the gravitational potential",

2011,*Astrophysics and Space Science*,**334(1)**, pp.71-74. -
I. Haranas, O.

**Ragos**and I. Gkigkitzis : "Horava-Lifshitz gravity: calculation of radar signal delay contribution in the vicinity of the Sun in the Kehagias-Sfetsos solution",

2011,*Astrophysics and Space Science*,**335(5)**, pp.539-543. -
I. Haranas, O.

**Ragos**and I. Gkigkitzis : "Radar signal delay in the Dvali-Gabadadze-Porrati gravity in the vicinity of the Sun",

2012,*Astrophysics and Space Science*,**342(1)**, pp.281-285. -
I. Haranas, O.

**Ragos**and I. Gkigkitzis : "Effects in the anomalistic period of celestial bodies due to a logarithmic correction to the Newtonian gravitational potential",

2013,*Astrophysics and Space Science*,**345(1)**, pp.67-72.

- O.
**Ragos**, M.N. Vrahatis and F.A. Zafiropoulos : "The topological degree for the computation of the total number of equilibrium points inODEs",

1995,*3rd International Colloquium on Numerical Analysis : Invited Lectures and Short Communications*(1994, Plovdiv, Bulgaria),

edited by D. Bainov and A. Dishliev, Sc. Cult. Techn. Publ., Singapore,pp.147-156. -
O.

**Ragos**and C.G. Zagouras : "A numerical algorithm for the determination of regions of quasi-periodic motion in two-dimensional Hamiltonian systems",

1995,*3rd International Colloquium on Numerical Analysis : Invited Lectures and Short Communications*(1994, Plovdiv, Bulgaria),

edited by D. Bainov and A. Dishliev, Sc. Cult. Techn. Publ., Singapore,pp.157-164. -
O.

**Ragos**, M.N. Vrahatis and F.A. Zafiropoulos : "The topological degree for the computation of the exact number of equilibrium points ofdynamical systems", 1994,*Proceedings of the 2nd Hellenic-European Conference on Mathematics and Informatics HERMIS 94*,

Athens, Greece, Vol.2, pp.533-542. -
O.

**Ragos**, M.N. Vrahatis and G.S. Androulakis : "Methods for thecomputation of periodic solutions of dynamical systems",

1996,*Proceedings of the Sixth International Colloquium on Differential Equations*(1995, Plovdiv, Bulgaria),

edited by D. Bainov, VSP, Netherlands, pp.213-220. -
O.

**Ragos**, M.N. Vrahatis and F.A. Zafiropoulos : "The computation of equilibrium points of up-to-three dimensional dynamical systems using thetopological degree theory",

1996,*Proceedings of the Sixth International Colloquium on Differential Equations*(1995, Plovdiv, Bulgaria),

edited by D. Bainov, VSP, Netherlands, pp.221-228. -
F.A. Zafiropoulos, T.N. Grapsa, O.

**Ragos**and M.N. Vrahatis : "Onthe computation of zeros of Bessel and Bessel-related functions",

1996,*Proceedings of the Sixth International Colloquium on Differential Equations*(1995, Plovdiv, Bulgaria),

edited by D. Bainov, VSP, Netherlands, pp.409-417. -
F.A. Zafiropoulos, O.

**Ragos**and M.N. Vrahatis : "Linear viscoelastic wave propagation",

1996,*Proceedings of the Sixth International Colloquium on Differential Equations*(1995, Plovdiv, Bulgaria),

edited by D. Bainov, VSP, Netherlands, pp.417-423. -
M.N. Vrahatis, O.

**Ragos**, F.A. Zafiropoulos and E.C. Triantafylou :"On the computation of all the equilibrium points in Hamiltonian systems with three degrees of freedom",

1999,*Proceedings of the NATO Advanced Study Institute on Hamiltonian Systems with Three or More Degrees of Freedom*(1995, S'Agaro, Spain),

edited by C. Simo, NATO ASI Series, Series C, Vol.533, Kluwer Academic Publishers, Netherlands, pp.638-641. -
M.N. Vrahatis, O.

**Ragos**and G.S. Androulakis : "A method for computing families of periodic orbits based on unconstrained oprimization",

1999,*Proceedings of the NATO Advanced Study Institute on Hamiltonian Systems with Three or More Degrees of Freedom*(1995, S'Agaro, Spain),

edited by C. Simo, NATO ASI Series, Series C, Vol.533, Kluwer Academic Publishers, Netherlands, pp.642-645. -
O.

**Ragos**, E.A. Perdios, V.S. Kalantonis and M.N. Vrahatis : "On the equilibrium points of the relativistic restricted three-body problem",

Proceedings of the Third World Congress of Nonlinear Analysis (2000, Sicily, Italy), edited by V. Lakshmikantham,

2001,*Nonlinear Analysis*,**47(5)**, pp.3413-3418. -
E.A. Perdios, O.

**Ragos**, A.E. Perdiou and M.N. Vrahatis : "Symmetric doubly asymptotic orbits in the photogravitational restricted three-body problem",

Proceedings of the Third World Congress of Nonlinear Analysis (2000, Sicily, Italy), edited by V. Lakshmikantham,

2001,*Nonlinear Analysis*,**47(5)**, pp.3443-3448. -
M.N. Vrahatis, O.

**Ragos**and G.S. Androulakis : "Computing families of periodic orbits through optimization methods",

Proceedings of the Third World Congress of Nonlinear Analysis (2000, Sicily, Italy), edited by V. Lakshmikantham,

2001,*Nonlinear Analysis*,**47(5)**, pp.3449-3454.