Changes
<ref name="AnOv">N. Anari, S. Oveis Gharan, ''Effective-Resistance-Reducing Flows, Spectrally Thin Trees, and Asymmetric TSP'', [http://arxiv.org/abs/1411.4613 arXiv link]</ref>
<ref name="BaSpSr">J. Batson, D.A. Spielman, N. Srivastava, ''Twice-Ramanujan Sparsifiers'', [http://arxiv.org/abs/0808.0163 arXiv link], [http://dx.doi.org/10.1137/090772873 DOI link]</ref>
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