World War, 1914-1918 -- Secret service -- Germany

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• World War, 1914-1918 -- Secret service
• World War, 1914-1918 -- Germany
• Secret service -- Germany

• German Spies at Bay: Being an Actual Record of the German Espionage in Great Britain During the Years 1914-1918, Compiled From Official Sources (New York: Brentano's, ca. 1920), by Sidney Theodore Felstead (page images at HathiTrust)
• Secrets of the White Lady (New York: G. P. Putnam's Sons, c1935), by Henry Landau (page images at HathiTrust)

Items below (if any) are from related and broader terms.

• Secrets of the White Lady (New York: G. P. Putnam's Sons, c1935), by Henry Landau (page images at HathiTrust)

• The Man with the Clubfoot (1918), by Valentine Williams (Gutenberg text)

• The Barbarism of Berlin, by G. K. Chesterton (Gutenberg text)
• Face to Face With Kaiserism (New York: George H. Doran Company, 1918), by James W. Gerard (illustrated HTML at BYU)
• Fighting for Peace (New York: Charles Scribner's Sons, 1917), by Henry Van Dyke (Gutenberg text)
• Hindenburg's March into London, Being a Translation From the German Original (London: John Long, 1916), by Paul Georg Münch, ed. by L. G. Redmond-Howard (multiple formats at archive.org)
• Histories of Two Hundred and Fifty-One Divisions of the German Army Which Participated in the War (1914-1918) (Washington: G.P.O., 1920), by United States Army (PDF at vlib.us; 49 MB)
• The Memoirs of the Crown Prince of Germany (1922), by Crown Prince of Germany William (multiple formats at archive.org)
• My Four Years in Germany (New York: George H. Doran Company, 1917), by James W. Gerard (illustrated HTML at BYU)
• My Four Years in Germany, by James W. Gerard (Gutenberg text)
• My Memoirs (2 volumes; New York: Dodd, Mead and Co., 1919), by Alfred von Tirpitz
  • Volume I: multiple formats at archive.org
  • Volume II: multiple formats at archive.org
• Out of My Life (London et al: Cassell and Company, 1920), by Paul von Hindenburg, trans. by F. A. Holt (multiple formats at archive.org)
• A War-Time Journal: Germany 1914, and German Travel Notes (London: E. Mathews, 1915), by Lady Jephson
  • multiple formats at archive.org
  • page images at HathiTrust; US access only

• The New Society (New York: Harcourt, Brace and Company, 1921), by Walther Rathenau, trans. by Arthur Windham (DjVu at Georgia)

• Die Ulmer Grenadiere an der Westfront: Geschichte des Grenadier-Regiments König Karl (5. Württ.) Nr. 123 im Weltkrieg 1914-1918 (in German; Stuttgart: C. Belser, 1920), by Richard Bechtle (page images at HathiTrust; US access only)