To cite the Risa package in publications use:

  Gonzalez-Beltran A., Neumann S., Maguire E., Rocca-Serra P., Sansone
  S.A. The Risa R/Bioconductor package: integrative data analysis from
  experimental metadata and back again BMC Bioinformatics, 2014,
  15(Suppl 1):S11

A BibTeX entry for LaTeX users is

  @Article{,
    author = {Alejandra Gonz\'{a}lez-Beltr\'{a}n and Steffen Neumann and Eamonn Maguire and Philippe Rocca-Serra and Susanna-Assunta Sansone},
    title = {{T}he {R}isa {R}/{B}ioconductor package: integrative data analysis
  from experimental metadata and back again},
    journal = {BMC Bioinformatics},
    year = {2014},
    volume = {15},
    pages = {(Suppl 1):S11},
    url = {http://www.biomedcentral.com/1471-2105/15/S1/S11},
  }