Columbia subject headings:
Harvard subject headings:
Education--France--Somme--History--19th century.
Teachers--France--Somme--History--19th century.
Teachers--France--Somme--Social conditions--19th century.
Princeton subject headings:
Education--France--Somme--History--19th century.
Teachers--France--Somme--History--19th century.
Teachers--France--Somme--Social conditions--19th century.