United States
Sources from the Federal Government, Military, and the Home Front.
Germany
Extensive collection of military documents and memoirs written by military commanders, as well as works by and about civilians.
Britain
Largely focused on military documents and memoirs.
Russian Empire
Collection of mostly diplomatic sources, with some military memoirs.
France
Includes several military documents and memoirs in the original French.
Italy
Lists many materials dealing with Italian diplomacy during the war.
Austria-Hungary
Several memoirs from military leaders and diplomats.
British Commonwealth Nations
Documents from Australia and New Zealand.
Entente Nations
Sources dealing with Serbia, Romania, Greece, Belgium, Portugal, and Montenegro.
Central Powers
Materials from the Ottoman Empire and Bulgaria.
