Monge, P., Fulk, J., Chatterjee, J., Heiss, B., Lee, S., Margolin, D., Shen, C., Stephens, K., & Weber, M. S. (2007, May). The structural evolution of organizational communities: How variation, selection and retention processes operate in NGO networks. Paper presented at the Annual Meeting of the International Network of Social Network Analysis, Corfu, Greece.