1. M. Barari and A. Razavi, Generalized Ricci solitons on twisted products, Çankaya university Journal of science and Engineering, 15(2) (2018), 76-87.
2. M. Bertola and Goutheir, Lie triple system and warped products, Rend. Math. Appl., 7 (21) (2001), 275-293.
3. A. L. Besse, Einstein manifolds, Ergebnisse der mathematics used threr Grenzgeiete, 3 (10), Springer-Verlag, Berlin, 1987.
4. R. L. Bishop, B. O’Nill, Manifolds of negative curvature, Trans. Am. Math. Soc., 145 (1969), 1-49.
5. S. Brendle, Rotational symmetry of Ricci solitons in higher dimensions, Journal of Differential Geometry, 97 (2014) 191-214.