Caponigri, A. Robert. "The Philosophy of Xavier Zubiri: An Introduction." From Realitas III-IV: 1976-1979, Madrid, 1979

Caponigri, A. Robert. "The Philosophy of Xavier Zubiri: An Introduction." From Realitas III-IV: 1976-1979, Madrid, 1979, Box: 160, Folder: 22. Julian Samora Papers, 24426265. Benson Latin American Collection, The University of Texas at Austin. https://archives.lib.utexas.edu/repositories/4/archival_objects/388760 Accessed September 27, 2026.