@Article{bollen2009clickstream,
  author = {Bollen, Johan and Van de Sompel, Herbert and Hagberg, Aric and Bettencourt, Luis and Chute, Ryan and Rodriguez, Marko A. and Balakireva, Lyudmila},
  title  = {Clickstream Data Yields High-Resolution Maps of Science},
  journal = {PLoS ONE},
  year   = {2009},
  number = {3},
  url    = {http://dx.doi.org/10.1371%2Fjournal.pone.0004803},
  doi = {10.1371/journal.pone.0004803},
  const  = {\ text}
}
@Article{bollen2009clickstream,
  author = {Bollen, Johan and van de Sompel, Herbert and Hagberg, Aric and Bettencourt, Luis and Chute, Ryan and Rodriguez, Marko A. and Balakireva, Lyudmila},
  title  = {Clickstream Data Yields High-Resolution Maps of Science},
  journal = {PLoS ONE},
  year   = {2009},
  number = {3},
  url    = {http://dx.doi.org/10.1371/journal.pone.0004803},
  doi = {10.1371/journal.pone.0004803},
  const  = {\ text}
}
@Misc{gomes-2005,
  author = {Gomes, Luiz H. and Almeida, Rodrigo B. and Bettencourt, Luis M. A. and Almeida, Virgilio and Almeida, Jussara M.},
  title  = {Comparative Graph Theoretical Characterization of Networks of Spam and  Legitimate Email},

  year   = {2005},
  number = {},
  url    = {http://www.citebase.org/abstract?id=oai:arXiv.org:physics/0504025},

  const  = {\ text}
}