BĂ–CKENHAUER, H.-J.; FORLIZZI, L.; HROMKOVIC, J.; KNEIS, J.; KUPKE, J.; PROIETTI, G.; WIDMAYER, P. On the Approximability of TSP on Local Modifications of Optimally Solved Instances. Algorithmic Operations Research, v. 2, n. 2, p. 83, 2 Sep. 2007.