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. 2014 Jul 16;9(7):e102007. doi: 10.1371/journal.pone.0102007

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© 2014 Louf et al

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.

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Total length of the railway network as a function of the country GDP . The dashed line shows the linear fit on the data points which gives .

Inline graphic — Total length of the railway network as a function of the country GDP . The dashed line shows the linear fit on the data points which gives .