Columbia subject headings:
Great Britain--History--Medieval period, 1066-1485.
Northumberland (England)--History.
Percy family.
Harvard subject headings:
England, Northern--History.
Great Britain--History--Henry IV, 1399-1413.
Great Britain--History--Richard II, 1377-1399.
Nobility--Great Britain--Biography
Percy family.
Princeton subject headings:
Great Britain--History--Medieval period, 1066-1485.
Northumberland (England)--History.
Percy family.