Select from four non-fiction books on German Spies!

Want an exciting read? What better than four books with real life stories of German Secret Service agents that brought terror, labor strikes, border incidents with Mexico, and subversive propaganda to the United States 100 years ago. E-books available on Amazon Kindle (look for Heribert von Feilitzsch or simply search "German Spies and Mexican Revolution" or "Sabotage and 1915").