SOURCES
http://en.wikipedia.org/wiki/Critical_mass_%28sociodynamics%29
http://wikicommedia.wikispaces.com/Umbrella+Perspective
http://en.wikipedia.org/wiki/Diffusion_%28business%29
Grant, August E. and Jennifer H. Meadows, eds. 2010. Communication Technology Update and Fundamentals, Twelfth Edition. New York: Elsevier.
Standage, Tom. 1998. The Victorian Internet: The Remarkable Story of the Telegraph and the Nineteenth Century's On-line Pioneers. New York: The Berkley Publishing Group.