To cite 'igraph' in publications use:

Wirth H, Loeffler M, vBergen M, Binder H: Expression cartography of human tissues using self organizing maps. BMC Bioinformatics 2011.

Corresponding BibTeX entry:

  @Article{,
    title = {Expression cartography of human tissues using self
      organizing maps.},
    author = {Henry Wirth and Markus Loeffler and Martin von Bergen and
      Hans Binder},
    journal = {BMC Bioinformatics},
    year = {2011},
  }