Three different centrality approaches will be considered in this work. The degree centrality is the simplest approach and corresponds to the number of connections of a specific node. A more complex concept is called betweenness centrality (b) which quantifies how often a node is crossed on the shortest pathway between two other nodes. The third concept, the eigenvector centrality (e), quantifies the influence of a certain node by assigning a relative score which takes into account that a connection to a high-scoring node contributes more to the score than a connection to nodes with a lower score.