This presentation from NSA’s Mathematics Research Group, dated 21 August 2008 provides an introduction to the XKeyScore system’s data sources and fingerprinting capabilities: see the SVT article FRA part of top-secret hacker project, 11 December 2013.
These undated slides from GCHQ’s National Defence Intelligence and Security Team claim that the agency collects “around 100,000,000 malware events per day”: see the Intercept article Popular Security Software Came Under Relentless NSA and GCHQ Attacks, 22 June 2015.
This October 2005 article, taken from the internal NSA newsletter Foreign Affairs Digest, provides a brief history of the agency’s past and current relationship with its Turkish counterparts, which includes a staff of 40 NSA employees stationed in Ankara: see the Intercept article How the NSA Helped Turkey Kill Kurdish Rebels, 31 August 2014.
This NSA information paper dated 8 April 2013 details the agency’s deepening signals intelligence relationship with Saudi Arabia: see the Intercept article The NSA’s New Partner in Spying: Saudi Arabia’s Brutal State Police, 25 July 2014.
This undated presentation from the NSA’s European Cryptologic Center explains some of the activities of the agency’s main European base: see the Der Spiegel article Terrorverdächtige: NSA nutzte Erkenntnisse aus Deutschland-Filiale für Tötungen, 15 June 2014.
This internal NSA post from 16 September 2003 describes one agency staffer’s experience of working at the NSA’s German stations: see the Der Spiegel article Spying Together: Germany’s Deep Cooperation with the NSA, 18 June 2014.
This Boundless Informant slide shows the number of German phone (DNR) and internet (DNI) records collected day-by-day between 10 December 2012 and 8 January 2013, from Third Party sources. The US-987LA sigad that accounts for the largest number of records is based in Germany: see the Der Spiegel article Spying Together: Germany’s Deep Cooperation with the NSA, 18 June 2014.
This internal NSA briefing document from 19 April 2014 supplies background information for a Strategic Planning Meeting with senior BND officers to discuss future collaboration between Germany and the US: see the Der Spiegel article Spying Together: Germany’s Deep Cooperation with the NSA, 18 June 2014.