1. S. Aleksic, Z. Kadelburg, Z. D. Mitrovic, et al. A new
2. i>Orthogonal sets: The axiom of choice and proof of a fixed point theore;H. Baghani, M. E. Gordji, M. Ramezani; J. Fixed Point Theory Appl.
3. V. V. Chistyakov, Modular metric spaces,
4. V. V. Chistyakov, Modular metric spaces,
5. S. H. Cho, J. S. Bae, Fixed point theorems for multivalued maps in cone metric spaces, Fixed Point Theory Appl., 2011 (2011), Article