P. Baird and &. J. Wood, Harmonic morphisms between Riemannian manifolds, Society Monographs, vol.29, 2003.
DOI : 10.1093/acprof:oso/9780198503620.001.0001

M. Berger, &. P. Gauduchon, and &. E. Mazet, Le spectre d'une variété Riemannienne, Lecture Notes in Mathem, vol.194, 1971.

E. Brieskorn, Beispiele zur Differentialtopologie von Singularit???ten, Inventiones Mathematicae, vol.144, issue.1, pp.1-14, 1966.
DOI : 10.1007/BF01403388

B. Chen, Geometry of submanifolds, Pure and Applied Math, 1973.

S. Chern, An elementary proof of the existence of isothermal parameters on a surface, Proceedings of the American Mathematical Society, vol.6, issue.5, pp.771-782, 1956.
DOI : 10.1090/S0002-9939-1955-0074856-1

S. Chern, &. P. Hartman, and &. A. Winter, On isothermic coordinates, Commentarii Mathematici Helvetici, vol.28, issue.1, pp.301-309, 1954.
DOI : 10.1007/BF02566936

S. Dragomir and &. L. Ornea, Locally conformal Kähler geometry, Progress in Mathematics, vol.155, 1998.

S. Dragomir and &. E. Lanconelli, Subelliptic harmonic morphisms, Osaka J. Math, vol.46, issue.2, pp.411-440, 2009.

S. Dragomir and &. G. Tomassini, On p-harmonic maps into spheres, Tsukuba Journal of Mathematics, vol.35, issue.2, pp.35-161, 2011.
DOI : 10.21099/tkbjm/1331658701

J. Eells and &. J. Ferreira, On Representing Homotopy Classes by Harmonic Maps, Bulletin of the London Mathematical Society, vol.23, issue.2, pp.160-162, 1991.
DOI : 10.1112/blms/23.2.160

J. Eells and &. J. Sampson, Harmonic Mappings of Riemannian Manifolds, American Journal of Mathematics, vol.86, issue.1, pp.109-160, 1964.
DOI : 10.2307/2373037

B. Fuglede, Harmonic morphisms between semi-Riemannian manifolds, Ann. Acad. Sci. Fennicae, vol.21, pp.31-50, 1996.

C. Godbillon, Géométrie différentielle et mécanique analytique, Collection Méthodes, 1968.

F. Helein, Sur la régularité des applications faiblement harmoniques entre une surface et une variété riemannienne, Séminairé Equations aux dérivées partielles (Polytechnique), pp.1-6, 1990.

S. Hu, Homotopy theory, 1959.

S. Ianus¸&ianus¸ianus¸& and M. Vis¸inescuvis¸inescu, Spontaneous compactification induced by non-linear scalar dynamics, gauge fields and submersions, Class. Quantum Grav, vol.3, pp.889-896, 1986.

T. Ishihara, A mapping of Riemannian manifolds which preserves harmonic functions, Journal of Mathematics of Kyoto University, vol.19, issue.2, pp.215-229, 1979.
DOI : 10.1215/kjm/1250522428

G. Jiang, 2-Harmonic maps and their first and second variation formulas, Chinese Ann, Math., Ser. A, vol.7, pp.389-402, 1986.

L. Lemaire, Applications harmoniques de surfaces riemanniennes, Journal of Differential Geometry, vol.13, issue.1, pp.51-78, 1978.
DOI : 10.4310/jdg/1214434347

L. Lemaire, Existence des applications harmoniques et courbure des variétés, Séminaire N. Bourbaki, 1979-1980, exp. n. 553, pp.174-195

P. Libermann, Sue les structures presque complexes et autres structures infinitésimales réguliers, Bull. Soc. Math. France, vol.83, pp.195-224, 1955.
DOI : 10.24033/bsmf.1460
URL : http://archive.numdam.org/article/BSMF_1955__83__195_0.pdf

E. Loubeau, Morphisms of the heat equation, Annals of Global Analysis and Geometry, vol.15, issue.6, pp.487-496, 1997.
DOI : 10.1023/A:1006534317200

E. Mazet, La formule de la variation seconde de l'´ energie au voisinage d'une application harmonique, J. Diff. Geometry, issue.2, pp.8-279, 1973.

K. Nomizu, Introduzione alla geometria differenziale, Appunti della Scuola Matematica Interuniversitaria, 1975.

C. Oniciuc, Biharmonic maps between Riemannian manifolds, An. S ¸ tiint¸.tiint¸, Univ. Al.I. Cuza, Ias¸iIas¸i, Mat, issue.202, pp.48-237

H. Rosenthal, Martingale proofs of a general integral representation theorem Analysis at Urbana II: Analysis in Abstract Spaces, Soc. Lecture Notes Ser, vol.138, pp.294-356, 1989.

R. T. Smith, The second variation formula for harmonic mappings, Proc. Amer, pp.229-236, 1975.
DOI : 10.1090/S0002-9939-1975-0375386-2

B. Solomon, Harmonic maps to spheres, Journal of Differential Geometry, vol.21, issue.2, pp.151-162, 1985.
DOI : 10.4310/jdg/1214439560

T. Takahashi, Minimal immersions of Riemannian manifolds, Journal of the Mathematical Society of Japan, vol.18, issue.4, pp.380-385, 1966.
DOI : 10.2969/jmsj/01840380

H. Urakawa, Calculus of variations and harmonic maps, Translations of Mathem. Monographs, vol.132, 1993.

I. Vaisman, Generalized Hopf manifolds, Geometriae Dedicata, pp.231-255, 1982.

M. Vis¸inescuvis¸inescu, Massless Kaluza-Klein Gauge Fields and Space-Time Compactification Induced by Scalars, Europhysics Letters (EPL), vol.4, issue.7, pp.767-770, 1987.
DOI : 10.1209/0295-5075/4/7/001