To cite sparr in publications use:

T. M. Davies, J. C. Marshall, M. L. Hazelton (2017). Tutorial on kernel estimation of continuous spatial and spatiotemporal relative risk with accompanying instruction in {R}; Submitted for publication. URL: https://arxiv.org/abs/1707.06888

Corresponding BibTeX entry:

  @Unpublished{,
    title = {Tutorial on kernel estimation of continuous spatial and
      spatiotemporal relative risk with accompanying instruction in
      {R}},
    author = {T. M. Davies and J. C. Marshall and M. L. Hazelton},
    note = {Submitted for publication},
    url = {https://arxiv.org/abs/1707.06888},
    year = {2017},
    pages = {1--30},
  }