1. Alcock, J. (2005). Animal behavior: An evolutionary approach (8th ed.). Sunderland, MA: Sinauer.
2. Angier, N. (2011, July 5). Thirst for fairness may have helped us survive. New York Times: Science Times.
3. Benjamin, S. P., & Zschokke, S. (2004). Homology, behavior and spider webs: Web construction behavior of Linyphia hortensis and L. Triangularis and its evolutionary significance. Journal of Evolutionary Biology, 17, 120–130.
4. Blechner, M. (1988). Differentiating empathy from therapeutic action. Contemporary Psychoanalysis, 24, 301–310.
5. Bracha, H. S. (2004). Freeze, flight, fight, faint: Adaptationist perspectives on the acute stress response spectrum. CNS Spectrums, 9, 679–685.