“…A significant portion of bibliometric analysis has been focused on citation analysis, which traces through citations and reveals the intellectual structure from a macro perspective. The representatives are direct citation (Garfield 2004), journal co-citation analysis (Hu et al 2011;Mustafee et al 2014), document co-citation analysis (Li et al 2010;Gao et al 2012), document bibliographic coupling (Ahlgren and Jarneving 2008), author co-citation analysis (ACA) (White and Griffith 1981;Chen and Lien 2011), and author bibliographic coupling (Zhao and Strotmann 2008a;Ma 2012). Another important branch of bibliometric analysis is content analysis, which relies on natural language processing to analyze large corpora of literature text and depicts the intellectual structure from a micro perspective.…”