REFERENCES
- Benzon, W. L., & Hays, D. G. (1990). The evolution of cognition. Journal of Social and Biological Structures, 13(4), 297–320,
- Lesher, J. (2011). Xenophanes. In Edward N. Zalta (Ed.), Stanford Encyclopedia of Philosophy. Stanford, CA: Stanford University. Retrieved from http://plato.stanford.edu/entries/xenophanes/
- Online Etymological Dictionary. (2001–2013). Douglas Harper. Retrieved on May 5, 2013, from http://www.etymonline.com/ index.php?search=spirit
- Semerano, G. (2001). L'infinito: un equivoco millenario. Le antiche civiltà del vicino oriente e le origini del pensiero greco. [The endlessness: a millenary misunderstanding. The oldest civilizations of the Middle East and the origins of the Greek thought]. Milan, Italy: Bruno Mondadori.