___

• [1] Adati, T. and Matsumoto, K., On conformally recurrent and conformally symmetric P - Sasakian manifolds, TRU Math., 13 (1977), 25–32.
• [2] Adati, T. and Miyazawa, T., On P -Sasakian manifolds admitting some parallel and recurrent tensors, Tensor (N.S.), 33 (1979), no. 3, 287–292.
• [3] Beem, J.K. and Ehrlich, P.E., Global Lorentzian geometry, Marcel Dekker, New York, 1981.
• [4] Blair, D.E., Contact manifolds in Riemannian geometry, Lectures Notes in Mathematics, Springer-Verlag, Berlin, 509 (1976), 146.
• [5] Blair, D.E., Kim, J.-S. and Tripathi, M.M., On the concircular curvature tensor of a contact metric manifold, J. Korean Math. Soc., 42 (2005), no. 5, 883–892.
• [6] Chaki, M.C. and Tarafdar, M., On a type of Sasakian manifold, Soochow J. Math., 16 (1990), no. 1, 23–28.
• [7] De, U.C. and Biswas, S., A note on ξ -conformally flat contact manifolds, Bull. Malays. Math. Sci. Soc. (2), 29 (2006), no. 1, 51–57.
• [8] De, U.C. and Ghosh, J.C., On a type of contact manifold, Note Mat., 14 (1994), no. 2, 155–160 (1997).
• [9] De, U.C., Jun, J.B. and Gazi, A.K., Sasakian manifolds with quasi-conformal curvature tensor, Bull. Korean Math. Soc., 45 (2008), no. 2, 313–319.
• [10] Deszcz, R., On Ricci-pseudosymmetric warped products, Demonstratio Math., 22 (1989), 1053–1065.
• [11] Duggal, K.L., Space time manifolds and contact structures, Internat. J. Math. Math. Sci., 13 (1990), 545–554.
• [12] Dwivedi, M.K. and Kim, J.-S., On conharmonic curvature tensor in K-contact and Sasakian manifolds, Bull. Malays. Math. Sci. Soc., 34 (2011), no. 1, 171–180.
• [13] Eisenhart, L.P., Riemannian Geometry, Princeton University Press, 1949. [14] Ishii, Y., On conharmonic transformations, Tensor (N.S.), 7 (1957), 73–80.
• [15] Ghosh, A. and Sharma, R., Some results on contact metric manifolds, Ann. Global Anal. Geom., 15 (1997), no. 6, 497–507.
• [16] Hong, S., Özgür, C. and Tripathi, M.M., On some classes of Kenmotsu manifold, Kuwait J. Sci. Engrg., 33 (2006), no. 2, 19–32.
• [17] Jun, J.-B., De, U.C. and Pathak, G., On Kenmotsu manifolds, J. Korean Math. Soc., 42 (2005), no. 3, 435–445.
• [18] Kenmotsu, K., A class of almost contact Riemannian manifold, Tˆohoku Math. J. (2), 24 (1972), 93–103.
• [19] Koufogiorgos, T., Contact metric manifolds, Ann. Global Anal. Geom., 11 (1993), no. 1, 25–34.
• [20] Koufogiorgos, T., Contact Riemannian manifolds with constant φ-sectional curvature, Tokyo J. Math., 20 (1997), no. 1, 13–22.
• [21] Maralabhavi, Y.B., On W -symmetric and W -recurrent Sasakian manifolds, J. Nat. Acad. Math. India, 4 (1986), no. 1-2, 63–72.
• [22] Matsumoto, K., On Lorentzian paracontact manifolds, Bull. Yamagata Univ. Nat. Sci., 12 (1989), no. 2, 151–156.
• [23] Miyazawa, T. and Yamaguchi, S., Some theorems on K-contact metric manifolds and Sasakian manifolds, TRU Math., 2 (1966), 46–52.
• [24] Mishra, R.S., On Sasakian manifolds, Indian J. Pure Appl. Math., 1 (1970), no. 1, 98–105.
• [25] Mishra, I.K. and Ojha, R.H., On para Sasakian manifolds, Indian J. Pure Appl. Math., 32 (2001), no. 9, 1309–1316.
• [26] Miyazawa, T. and Yamaguchi, S., Some theorems on K-contact metric manifolds and Sasakian manifolds, TRU Math., 2 (1966), 46–52.
• [27] Nomizu, K. and Ozeki, H., A theorem on tensor fields, Proc. Nat. Acad. Sci. U.S.A., 48 (1962), 206–207.
• [28] Okumura, M., Some remarks on space with a certain contact structure, Tˆohoku Math. J. (2), 14 (1962), 135–145.
• [29] Ojha, R.H., M -projectively flat Sasakian manifolds, Indian J. Pure Appl. Math., 17 (1986), no. 4, 481–484.
• [30] O’Neill, B., Semi-Riemannian geometry with applications to relativity, Academic Press, New York, London, 1983.
• [31] Özgür, C., On a class of para-Sasakian manifold, Turk. J. Math., 29 (2005), 249–257.
• [32] Özgür, C. and De, U.C., On the quasi-conformal curvature tensor of a Kenmotsu manifold, Math. Pannon., 17 (2006), no. 2, 221–228.
• [33] Özgür, C. and Tripathi, M.M., On P -Sasakian manifolds satisfying certain conditions on the concircular curvature tensor, Turkish J. Math., 31 (2007), no. 2, 171–179.
• [34] Pandey, S.N. and Verma, S., On para-Sasakian manifold, Indian J. Pure Appl. Math., 30 (1999), no. 1, 15–22.
• [35] Perrone, D., Contact Riemannian manifolds satisfying R(X, ξ) · R = 0, Yokohama Math. J., 39 (1992), no. 2, 141–149.
• [36] Pokhariyal, G.P. and Mishra, R.S., Curvature tensors and their relativistic significance, Yoko- hama Math. J., 18 (1970), 105–108.
• [37] Pokhariyal, G.P. and Mishra, R.S., Curvature tensors and their relativistic significance II, Yokohama Math. J., 19 (1971), no. 2, 97–103.
• [38] Pokhariyal, G.P., Relativistic significance of curvature tensors, Internat. J. Math. Math. Sci., 5 (1982), no. 1, 133–139.
• [39] Prasad, B., A pseudo projective curvature tensor on a Riemannian manifold, Bull. Calcutta Math. Soc., 94 (2002), no. 3, 163–166.
• [40] Rahman, M.S., A study of para-Sasakian manifolds, International Atomic Energy Agency and United Nations Educational Scientific and Cultural Organization, International Centre for Theoretical Physics, Internal Report, 1995.
• [41] Sasaki, S., On differentiate manifolds with certain structures which are closely related to almost contact structure I, Tˆohoku Math. J., 12 (1960), 459–476.
• [42] Satö, I., On a structure similar to the almost contact structure, Tensor (N.S.), 30 (1976), no.3, 219–224.
• [43] Satö, I. and Matsumoto, K., On P -Sasakian manifold satisfying certain conditions, Tensor (N.S.), 33 (1979), 173–178.
• [44] Sharfuddin, A., Deshmukh, S. and Husain, S.I., On para-Sasakian manifolds, Indian J. Pure Appl. Math., 11 (1980), no. 7, 845–853.
• [45] Szabó, Z.I., Structure theorems on Riemannian manifolds satisfying R(X, Y ) · R = 0, I, Local version, J. Diff. Geom., 17 (1982), 531–582.
• [46] Takagi, H., An example of Riemannian manifold satisfying R(X, Y ) · R = 0 but not ∇R = 0, Tˆohoku Math. J., 24 (1972), 105–108.
• [47] Takahashi, T., Sasakian manifold with pseudo-Riemannian metric, Tˆohoku Math J., 21 (1969), 271–290.
• [48] Tanno, S., Ricci curvatures of contact Riemannian manifolds, Tˆohoku Math J., 40 (1988), 441–448.
• [49] Tarafdar, M. and Mayra, A., On P -Sasakian manifold, I˙stanb. U¨ niv. Fen Fak. Mat. Fiz. Astron. Derg., 53 (1994), 73–76 (1996).
• [50] Tarafdar, M. and Sengupta, A.K., On a type of contact manifolds, Anal. Stint Ale Univ. “ Al. I. Cuza” Iasi, 47 (2001), no.1, 73–78 (2002).
• [51] Tripathi, M.M., Kılı¸c, E., Yüksel Perkta¸s, S. and Kele¸s, S., Indefinite almost paracontact metric manifolds, Internat. J. Math. Math. Sci., 2010 (2010), 19 pp. Art. ID 846195.
• [52] Tripathi, M.M. and Gupta, P., T -curvature tensor on a semi-Riemannian manifolds, Jour. Adv. Math. Stud., 4 (2011), no. 1, 117–129.
• [53] Walker, A.G., On Ruse’s spaces of recurrent curvature, Proc. London Math. Soc., 50 (1950), 36–64.
• [54] Yano, K., Concircular Geometry I. Concircular transformations, Math. Institute, Tokyo Im- perial Univ. Proc., 16 (1940), 195–200.
• [55] Yano, K. and Bochner, S., Curvature and Betti numbers, Annals of Mathematics Studies 32, Princeton University Press, 1953.
• [56] Yano, K. and Sawaki, S., Riemannian manifolds admitting a conformal transformation group, J. Diff. Geom., 2 (1968), 161–184.