^ abcThe Middle Ages: an Illustrated History. Barbara A. Hanawalt. Oxford University Press, New York, 1998. ISBN 0-19-510359-9
^M. M. Postan and Edward Miller (1987). The Cambridge Economic History of Europe, Vol. II: Trade and Industry in the Middle Ages (2nd ed. ed.). Cambridge University Press. pp. pp. 378–379. ISBN0521087090
^John Reader,. Cities: A Magisterial Exploration of the Nature and Impact of the City from Its Beginnings to the Mega-Conurbations of Today. Boston: Atlantic Monthly Press. pp. p. 94. ISBN0-87113-898-0