See S. Toy, History of Fortification from 3000 B.C. to A.D. 1700 (1955); W. D. Simpson, Castles in Britain (1966); A. Weissmüller, Castles from the Heart of Spain (1967); W. Anderson, Castles of Europe from Charlemagne to the Renaissance (1971); P. Warner, The Medieval Castle (1972).
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.