1. Althöfer, I.: Personal Communication in June 2014
2. Althöfer, I., Beckmann M., Salzer. F.: On some random walk games with diffusion control (2015)
3. Durrett, R.: Probability: Theory and Examples (2010).
http://www.math.duke.edu/ rtd/PTE/PTE4_1.pdf
. Accessed on 9th March 2015
4. Section 5.9 in Mathematical Constants;SR Finch,2003
5. Maxwell, J.C.: Theory of Heat, 9th edn. Longmans, London (1888)