Columbia subject headings:
Coal miners--Labor unions--Officials and employees--Wales--Biography.
Labour Party (Great Britain)--History.
Prothero, Cliff, 1898-
Strikes and lockouts--Coal mining--Wales--History.
Harvard subject headings:
Coal miners--Labor unions--Officials and employees--Wales--Biography.
Coal miners--Labor unions--Wales--Officials and employees--Biography.
Labour Party (Great Britain)--History.
Prothero, Cliff, 1898-
Strikes and lockouts--Coal mining--Wales--History.
Princeton subject headings:
Labour Party (Great Britain)--History--20th century.
Prothero, Cliff, 1898-