City walls : the urban enceinte in global perspective - Tracy, James D.; Asher, Catherine B.; Bachrach, Bernard S.; Blair, Sheila S.; Bloom, Jonathan M.; Connah, Graham; Cooper, Frederick A.; Elbl, Martin M.; Farmer, Edwaed L.; Kagan, Richard L.; Milner, Georg R.; Parker, Geoffrey; et al. (Studies in comparative early modern history, 2000)