You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: The Forwarding Indices of Graphs -- a Survey 
Chapter Title:  Relations to Other Topics 
1. Abstract of Cited Paper (BIB001):  For a connected graph G of order n ≥ 2 with positive Laplacian eigenvalues λ2,...,λn, let b(G) = n-1 1/λ2 + ... + 1/λn. In this note we derive bounds on some graph invariants (edge-density in cuts, isoperimetric number, mean distance, edge-forwarding index, edge connectivity, etc) in terms of b(G).

Literature Review:
To the knowledge of the author, until now one has not yet find an approximation algorithm with good performance ratio for finding routings of general graphs. However, de le Vega and Manoussakis  showed that the problem of determining the value of the forwarding index (respectively, the forwarding index of minimal routings) is an instance of the multicommodity flow problem (respectively, flow with multipliers). Since many very good heuristics or approximation algorithms are known for these flow problems BIB001   , it follows from these results that all of these algorithms can be used for calculating the forwarding index. Teranishi BIB002 , Laplacian spectra and invariants of graphs.