ARQ acknowledges the author for sharing her research with us and agreeing to translate it to Spanish, and also to Taylor and Francis Group for granting us the permission to republish its English version.
Miguel Lawner, Justo Pastor Mellado, Daniel Talesnik, y Francisco Díaz me dieron valiosos comentarios, que me permiten presentar esta nueva versión en español, revisada y editada, para mayor alcance y difusión.