Babahmed, M., A. El Amrani, and S. Lazaiz. “Fixed Points and Diametral Sets for Sequentially Bounded Mappings in Orbital Ultrametric Spaces”. Proyecciones (Antofagasta, On Line), vol. 39, no. 2, Apr. 2020, pp. 481-93, doi:10.22199/issn.0717-6279-2020-02-0030.