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The mass-distance relation ℳ(d). (a) Core of PIN of yeast obtained by Ito et al. (16). (b) Metabolic networks of eukaryotes. Data are averaged over all five organisms in ref. 7. Note that in this case we count only substrates for ℳ(d). (c) Internet AS as of October, 2001. (d) WWW of www.nd.edu.
