1. Bejan, C.-L.: A classification of the almost Para-Hermitian manifolds. In: Differential Geometry and its Applications (Bokan, N. et al., eds.), Proceedings of the Conference Dubrovnik, 1988, University of Novi Sad, Institute of Mathematics, Novi Sad, 23–27 (1989)
2. Bejan, C.-L.: Some examples of manifolds with hyperbolic structures. Rend. Mat. Appl. 14, 557–565 (1994)
3. Bejan, C.-L., Eken, Ş.: A characterization of the Riemann extension in terms of harmonicity. Czechoslov. Math. J. 67(142), 197–206 (2017)
4. Bejan, C.-L., Kowalski, O.: On some differential operators on natural Riemann extensions. Ann. Glob. Anal. Geom. 48, 171–180 (2015)
5. Bejan, C.-L., Meriç, Ş.E., Kiliç, E.: Einstein metrics induced by natural Riemann extensions. Adv. Appl. Clifford Algebr. 27(3), 2333–2343 (2017)