“…In parallel, engineers, economists, and geographers gradually adopted such a framework, mainly confirming the already observed scale-free and small-world macro-structure (Ducruet and Notteboom, 2012;Hu and Zong, 2013;Kang et al, 2014;Liu et al, 2018;Pan et al, 2019). Some of them discussed the effect of node aggregation at different scales (Tsiotas and Polyzos, 2018;Wang et al, 2019a), while others studied the global maritime network with the world region as the unit of analysis (Tran and Haasis, 2014;Li et al, 2015;Xu et al, 2015). A large body of literature focused on ranking ports by centrality indicators, introducing more or less novelty (Wang and Cullinane, 2008;Lam and Yap, 2011;Montes et al, 2012;Cullinane and Wang, 2012;Doshi et al, 2012;Freire Seoane et al, 2013;Wang and Cullinane, 2014;Kang et al, 2014;Bartholdi et al, 2016).…”