Columbia subject headings:
Catholic Church--France--Laon--Bishops--History--Sources.
Laon (France)--Church history--Sources.
Harvard subject headings:
Catholic Church--France--Laon--Bishops--History--Sources.
Laon (France)--Church history--Sources.
Princeton subject headings:
Catholic Church--France--Laon--Bishops--History--Sources.
Laon (France)--Church history--Sources.