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2017, Konglin Zhu, Xiaoming Fu, Wenzhong Li, Sanglu Lu, Jan Nagler, “Population Growth in Online Social Networks”, in Xiaoming Fu, Jar-Der Luo, Margarete Boos, editors, Social Network Analysis: Interdisciplinary Approaches and Case Studies, CRC Press, section 3 (The Data), subsection 1 (Three Online Social Networks)