To cite package 'agop' in publications use:

Gagolewski M., Cena A. (2013). agop: Aggregation Operators package for R. http://www.rexamine.com/resources/agop/.

Corresponding BibTeX entry:

  @Manual{,
    title = {agop: Aggregation Operators package for R},
    author = {Marek Gagolewski and Anna Cena},
    year = {2013},
    url = {http://www.rexamine.com/resources/agop/},
  }