References
- Budiansky, S. 2005. Her Majesty's Spymaster. New York: Penguin Group.
- Gilbert, J. L. 2012. World War I and the Origins of U.S. Military Intelligence. Lanham, MD: Scarecrow Press, Inc.
- Herodotus. 1920. The Histories. Translated by A. D. Godley. Vol. 5. Chapter 35. Cambridge, MA: Harvard University Press. http://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:1999.01.0126:book=5:chapter=35 (accessed 16 December 2014).
- Hunter, L. W., and S. A. Handford. 1927. Aeneas on Siegecraft. Oxford: Clarendon Press. Greek text, English translation. http://demonax.info/doku.php?id=text:how_to_survive_under_siege (accessed 2 December 2014).
- Yardley, H. O. 1931. The American Black Chamber. Indianapolis: Bobbs-Merrill Publishing.
- Zielinska, E., W. Mazurczyk, and K. Szczypiorski. 2014. Trends in Steganography, Communications of the ACM, 57(3): 86–95.