[Air-L] Literature on dimensions/attributes of online communities?

Hello all, I'm beginning a project that is focused on making distinctions between different Twitter hashtags based on the type and/or "amount" of community that is present in each. Because I'm relatively new to online communities, I want to make sure I'm not missing important work in this area. Are there any resources that you would recommend for thinking about what makes up an online community and what distinguishes different online communities from each other? Many thanks! Best, Spencer ------ Spencer Greenhalgh PhD Candidate, Educational Psychology and Educational Technology Michigan State University spencergreenhalgh.com twitter.com/spgreenhalgh