Books in World War I (sorted alphabetically)
- Rebuilding Britain: A Survey of Problems of Reconstruction After the World War Sir Alfred Hopkinson
- Red Cross Girls with Pershing to Victory Margaret Vandercook
- Red Cross Girls with the Russian Army Margaret Vandercook
- Red Flower: Poems Written in War Time Henry Van Dyke
- Red Horizon Patrick MacGill
- Retreat from Mons George Stuart Gordon
- Riddle of the Rhine: Chemical Strategy in Peace and War Victor Lefebure
- Rogers-isms, the Cowboy Philosopher on the Peace Conference Will Rogers
- rote Kampfflieger (German) Freiherr von Manfred Richthofen
- Rounding up the Raider: A Naval Story of the Great War Percy F. Westerman
- Russian Advance Marr Murray
- Ruth Fielding at the War Front; or, The Hunt for the Lost Soldier Alice B. Emerson
- Salvaging of Civilization H. G. Wells
- Same old Bill, eh Mable!" Edward Streeter
- Schemes of the Kaiser Juliette Adam
- School History of the Great War Albert E. McKinley, Charles Augustin Coulomb, and Armand Jacques Gerson
- Sea-Hounds Lewis R. Freeman
- Secret Battle A. P. Herbert
- Secret Memoirs of Bertha Krupp Henry W. Fischer
- Sequel George A. Taylor
- Serbia in Light and Darkness Nikolaj Velimirović
- Sergeant York And His People Sam K. Cowan
- Seventeenth Highland Light Infantry (Glasgow Chamber of Commerce Battalion) : Record of War Service, 1914-1918
- Seventh Manchesters: July 1916 to March 1919 S. J. Wilson
- Shelled by an Unseen Foe James Fiske