Columbia subject headings:
Language policy--Wales.
Linguistic geography.
Maps.
Welsh language--Maps.
Welsh language.
Harvard subject headings:
Language policy--Wales.
Linguistic geography.
Welsh language--20th century--History.
Welsh language--20th century--Maps.
Welsh language--20th century--Statistics.
Welsh language--Maps.
Welsh language.
Princeton subject headings:
Linguistic geography.
Welsh language.