Wiener index of graphs with more than one cut-vertex

For a simple connected undirected graph GG, the Wiener index  W(G)W(G) is defined as half the sum of all distances of the form d(u,v)d(u,v), where the summation is over all possible vertex pairs u,vu,v in GG. Assuming that GG has more than one cut-vertex, we obtain an expression for W(G)W(G) in terms of the Wiener indices of the blocks of GG and other quantities.