To cite ParallelPC in publications use:

  Thuc Duy Le, Tao Hoang, Jiuyong Li, Lin Liu, Shu Hu (2015).
  ParallelPC: an R package for efficient constraint based causal
  exploration. arXiv preprint arXiv:1510.03042.
  http://arxiv.org/pdf/1510.03042.pdf.

A BibTeX entry for LaTeX users is

  @Article{,
    title = {ParallelPC: an R package for efficient constraint based causal exploration},
    author = {Thuc Duy Le and Tao Hoang and Jiuyong Li and Lin Liu and Shu Hu},
    journal = {rXiv preprint arXiv},
    year = {2015},
    volume = {1510},
    number = {03042},
    url = {http://arxiv.org/pdf/1510.03042.pdf},
  }