Columbia subject headings:
Great Britain--Emigration and immigration--History--20th century.
Ireland--Emigration and immigration--History--20th century.
Ireland--History--20th century.
Ireland--Population--History--20th century.
Irish--Great Britain--History--20th century.
Harvard subject headings:
Great Britain--Emigration and immigration--History--20th century.
Ireland--Emigration and immigration--History--20th century.
Ireland--History--20th century.
Ireland--Population--History.
Princeton subject headings:
Great Britain--Emigration and immigration--History.
Great Britain--History--20th century.
Ireland--Emigration and immigration--History.
Ireland--History--20th century.