To cite sparr in publications use:

Davies TM, Marshall JC, Hazelton ML (2018). “Tutorial on kernel estimation of continuous spatial and spatiotemporal relative risk.” Statistics in Medicine, 37(7), 1191–1221.

Corresponding BibTeX entry:

  @Article{,
    title = {Tutorial on kernel estimation of continuous spatial and
      spatiotemporal relative risk},
    author = {T. M. Davies and J. C. Marshall and M. L. Hazelton},
    journal = {Statistics in Medicine},
    year = {2018},
    volume = {37},
    number = {7},
    pages = {1191--1221},
  }