1. Aaker, D. (2008) Spanning Silos: The New CMO Imperative. Boston, MA: Harvard University Press.
2. Gerzema, J. and Lebar, E. (2008) The Brand Bubble. San Francisco, CA: Jossey-Bass.
3. More details on the brand energizer concept can be found in Aaker, D. (2004) Brand Portfolio Strategy. New York: The Free Press, pp. 144–153.