1. von Arnim, Andreas. 1999. Private security companies and internal security in Europe. In Recht und Organisation privater Sicherheitsdienste in Europa, ed. Reinhard Ottens, Harald Olschok, and Stephan Landrock, 61–112. Stuttgart: R. Boorberg.
2. Article 29 Working Party. 2010. Opinion 3/2010 on the principle of accountability. Brussels: Article 29 Working Party. http://ec.europa.eu/justice/policies/privacy/docs/wpdocs/2010/wp173_en.pdf. Accessed 28 July 2011.
3. Bennett, Colin J., and Charles D. Raab. 2006. The governance of privacy: Policy instruments in global perspective. 2nd and updated ed. Cambridge: MIT Press.
4. Bukow, Sebastian. 2005a. Deutschland: Mit Sicherheit weniger Freiheit über den Umweg Europa. In Europäisierung der inneren Sicherheit, ed. Gert-Joachim Glaeßner and Astrid Lorenz, 43–62. Wiesbaden: VS Verlag.
5. Bukow, Sebastian. 2005b. Internal security and the fight against terrorism in Germany. Philosophische Fakultät III Institut für Sozialwissenschaften, Humboldt Universität Berlin. http://edoc.hu-berlin.de/oa/conferences/reZgVweZSLueU/PDF/27QEOto3iuZCs.pdf. Accessed 30 July 2011.