Columbia subject headings:
Crusades--Fourth, 1202-1204.
Istanbul (Turkey)--History--Siege, 1203-1204.
Harvard subject headings:
Crusades--Fourth, 1202-1204--Early works to 1800.
Istanbul (Turkey)--History--Siege, 1203-1204--Early works to 1800.
Princeton subject headings:
Crusades--Fourth, 1202-1204.
Istanbul (Turkey)--History--Siege, 1203-1204.