To cite TractoR (of which 'tractor.base' is part) in publications, please use:

Clayden JD, Muñoz Maniega S, Storkey AJ, King MD, Bastin ME, Clark CA (2011). “TractoR: Magnetic resonance imaging and tractography with R.” Journal of Statistical Software, 44(8), 1–18. doi:10.18637/jss.v044.i08.

Corresponding BibTeX entry:

  @Article{tractor-paper,
    title = {{TractoR}: Magnetic resonance imaging and tractography
      with {R}},
    author = {Jonathan D Clayden and Susana {Muñoz Maniega} and Amos J
      Storkey and Martin D King and Mark E Bastin and Chris A Clark},
    journal = {Journal of Statistical Software},
    year = {2011},
    volume = {44},
    number = {8},
    pages = {1--18},
    doi = {10.18637/jss.v044.i08},
  }