{"id":"000998073","type":"book","title":"The construction of Frankish circular fortresses in the province of Zeeland (SW Netherlands) in the end of the ninth century","publisher":"Centre de Recherche Archéologique Médiévales","publisher-place":"Caen","pages":"241-249","container-title":"Château Gaillard. 18. Études de castellologie médiévale. Actes du Colloque International tenu à Gilleleje (Danemark), 24-30 août 1996","author":[{"family":"Heeringen","given":"Robert M. van"}],"issued":{"raw":"1998"}}