1. [1] A. A. Shaikh and K. K. Baishya, On ϕ-symmetric LP-Sasakian manifolds, Yokohama Math. J., 52, (2005), 97–112.
2. [2] A. A. Shaikh and K. K. Baishya, Some results on LP-Sasakian manifolds, Bull. Math. Soc. Sc. Math. Rommanic, Tome 49(97), (2006), 197–208.
3. [3] A. A. Shaikh, T. Basu, and K. K. Baishya, On the exixtence of locally ϕ-recurrent LP-Sasakian manifolds, Bull. Allahabad Math. Soc., 24(2), (2009), 281–295.
4. [4] B. J. Papantoniou, Contact Riemannian manifolds satisfying R(ξ, X) · R = 0 and ξ ∈ (k, μ)-nullity distribution, Yokohama Math. J., 40, (1993), 149–161.
5. [5] D. Perrone, Contact Riemannian manifolds satisfying R(ξ, X) · R = 0, Yokohama Math. J., 39(2), (1992), 141–149.