Columbia subject headings:
Cromwell, Oliver, 1599-1658.
Great Britain--History--Commonwealth and Protectorate, 1649-1660--Sources.
Harvard subject headings:
Cromwell, Oliver, 1599-1658
Great Britain--Politics and government--1642-1660.
Princeton subject headings:
Cromwell, Oliver, 1599-1658.
Great Britain--History--Commonwealth and Protectorate, 1649-1660--Sources.