  One of the more recent measures of centrality in social network analysis is
the normalized harmonic centrality. A variant of the closeness centrality,
harmonic centrality sums the inverse of the geodesic distances of each node to
other nodes where it is 0 if there is no path from one node to another. It is
then normalized by dividing it by m-1, where m is the number of nodes of the
graph. In this paper, we present notions regarding the harmonic centrality of
some important classes of graphs.
