There are a wide range of blogs describing strategies to increase the reach on Facebook but I am having problem finding peer-reviewed papers on this topic. Are you aware of some peer-reviewed papers about the reach on Facebook?
If you are talking about expanding the population of people using Facebook, you should look at some of Susan Wyche's work on technology use in Africa. She has a CSCW paper this year entitled "Facebook in the Developing World: The Myths and Realities Underlying a Socially Networked World."
As a starting place you might take a look at Jan Boehmer's work on the relationship between liking a link on Facebook and browsing behavior on the linked website. It isn't quite what you are looking for, but his citations might be a good starting place.
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