Columbia subject headings:
English drama--20th century--History and criticism.
Theater--England--London.
Theater--Great Britain.
Harvard subject headings:
English drama--20th century--History and criticism
Theater--England--London--History--20th century.
Theater--England--London.
Theater--Great Britain--History--20th century
Theater--Great Britain.
Princeton subject headings:
English drama--20th century--History and criticism.
Theater--England--London.
Theater--Great Britain.