(Nairobi: Camerapix,1992) Around Africa: From the Pillars of Hercules to the StraitofGibraltar (London: Simon & Schuster, 1994) Celtic Gold: A Voyage Around
University Press. O'Callaghan, Joseph F. (2011). The Gibraltar Crusade: Castile and the Battle for the Strait. Philadelphia: University of Pennsylvania Press.
O'Callaghan, Joseph F. (2011). The Gibraltar Crusade: Castile and the Battle for the Strait. Philadelphia: University of Pennsylvania Press. Salvador Martínez