To cite package ‘Rcpi’ in publications use:

  Dong-Sheng Cao, Nan Xiao, Qing-Song Xu, and Alex F. Chen. (2015).
  Rcpi: R/Bioconductor package to generate various descriptors of
  proteins, compounds and their interactions. Bioinformatics 31 (2),
  279-281.

A BibTeX entry for LaTeX users is

  @Article{cao2015rcpi,
    title = {Rcpi: R/Bioconductor package to generate various descriptors of proteins, compounds and their interactions},
    author = {Dong-Sheng Cao and Nan Xiao and Qing-Song Xu and Alex F. Chen},
    journal = {Bioinformatics},
    volume = {31},
    number = {2},
    pages = {279--281},
    year = {2015},
    doi = {10.1093/bioinformatics/btu624},
  }