To cite package 'blockTools' in publications use:

Moore, Ryan T. (2014). blockTools: Blocking, Assignment, and Diagnosing Interference in Randomized Experiments. R package version 0.5-8.

Corresponding BibTeX entry:

  @Manual{,
    title = {blockTools: Blocking, Assignment, and Diagnosing
      Interference in Randomized Experiments},
    author = {Ryan T. Moore},
    year = {2014},
    note = {R package version 0.5-8},
  }