E. Martínez-Fortún Medrano, “Español Correspondence in the process of identifying the photographs of León Martínez-Fortún Erlés in the photographic collection of the Martínez-Fortún Fonds of the Municipal Archive of Valladolid”, Rev. gen. inf. doc., vol. 35, no. 1, pp. 63–80, Jul. 2025, doi: 10.5209/rgid.98938.