To cite SpatialPack in publications use:

Vallejos R, Osorio F, Bevilacqua M (2020). Spatial Relationships Between Two Georeferenced Variables: with Applications in R. Springer, New York. ISBN 978-3-030-56680-7, http://srb2gv.mat.utfsm.cl/.

Corresponding BibTeX entry:

  @Book{,
    title = {Spatial Relationships Between Two Georeferenced Variables:
      with Applications in R},
    author = {R. Vallejos and F. Osorio and M. Bevilacqua},
    publisher = {Springer},
    address = {New York},
    year = {2020},
    note = {ISBN 978-3-030-56680-7},
    url = {http://srb2gv.mat.utfsm.cl/},
  }