L. Wheeler, C. Opello Douglas, Walter (2010)։ Historical Dictionary of Portugal։ Scarecrow Press։ ISBN978-0-8108-6088-9
Runciman Steven (1952)։ A History of the Crusades, vol. II: The Kingdom of Jerusalem and the Frankish East, 1100–1187։ New York: Cambridge University Press
Brundage James (1962)։ The Crusades: A Documentary History։ Milwaukee, Wisconsin: Marquette University Press
↑C. W. David, "The Authorship of the De Expugnatione Lyxbonensi", Speculum, 7:1 (1932), 50, citing Helmold's Chronica Slavorum in MGH, Scriptores, 11, 58: Hoc solum prospere cessit de universo opere, quod peregrinus patravit exercitus.