To cite GeoXp in publications use:

Thibault Laurent, Anne Ruiz-Gazen, Christine Thomas-Agnan (2012). GeoXp: An R Package for Exploratory Spatial Data Analysis. Journal of Statistical Software, 47(2), 1-23. URL http://www.jstatsoft.org/v47/i02/.

Corresponding BibTeX entry:

  @Article{,
    title = {{GeoXp}: An {R} Package for Exploratory Spatial Data
      Analysis},
    author = {Thibault Laurent and Anne Ruiz-Gazen and Christine
      Thomas-Agnan},
    journal = {Journal of Statistical Software},
    year = {2012},
    volume = {47},
    number = {2},
    pages = {1--23},
    url = {http://www.jstatsoft.org/v47/i02/},
  }