http://www.amazon.com/Tipping-Point-Little-Things-Difference/dp/0316346624|Epidemics at Large|
by Malcom Gladwell
The basic premise on this book is that epidemics can be thought as a general pattern appliable as well to health, social phenomena or technology. A very well written book, Gladwell makes a extensive investigation, gathers information that may seem disgragated and elaborates a proposition. Not a scientific method traditional approach, but a good starting point to the understanding and use of this knowledge.