Thanks, CIA. . .

for the great articles on espionage before, during and after the Great War.  Here are some of the articles the agency has made available at their website:

Allen Dulles During the War

The Exploits of Agent 110: Allen Dulles in Wartime

https://www.cia.gov/library/center-for-the-study-of-intelligence/kent-csi/vol37no1/html/v37i1a05p_0001.htm

The Kaiser Sows Destruction

https://www.cia.gov/library/center-for-the-study-of-intelligence/csi-publications/csi-studies/studies/vol46no1/article02.html

Okhrana Agent Dolin

https://www.cia.gov/library/center-for-the-study-of-intelligence/kent-csi/vol10no2/html/v10i2a06p_0001.htm

Revolutionary Propagandist & Agent V.L. Burtzev

The Sherlock Holmes of the Revolution: Vladimir Lvovich Burtzev

https://www.cia.gov/library/center-for-the-study-of-intelligence/kent-csi/vol11no4/html/v11i4a07p_0001.htm

The Lohmann Affair: The Weimar Republic's Attempts to Circumvent the Versailles Restrictions

https://www.cia.gov/library/center-for-the-study-of-intelligence/kent-csi/vol4no2/html/v04i2a08p_0001.htm