Answer
Yes, Santos was co-founder of Nueva Dimensión magazine. In 1966, Santos helped found the magazine with Mario Hernández and Rafael Álvarez-Quintero. The magazine published a variety of science fiction and fantasy stories, including work by Isaac Asimov, Arthur C. Clarke, and Ray Bradbury. It was one of the first Spanish-language science fiction magazines in the world, and helped to introduce science fiction to a wider audience in Latin America.