Columbia subject headings:
Harvard subject headings:
Battlefields--France--Somme--Guidebooks.
France--History, Military.
Somme (France)--History.
Somme, 1st Battle of the, France, 1916.
Somme, 2nd Battle of the, France, 1918.
Princeton subject headings:
Battlefields--France--Somme.
Somme (France)--History.