To cite the R package 'dlnm' in publications use:

Gasparrini A, Armstrong B, Scheipl F (2011). “Distributed lag linear and non-linear models in R: the package dlnm.” Journal of Statistical Software, 43(8), 1–20. doi:10.18637/jss.v043.i08, https://doi.org/10.18637/jss.v043.i08.

A BibTeX entry for LaTeX users is returned by: toBibtex(citation('dlnm'))

Corresponding BibTeX entry:

  @Article{,
    title = {Distributed lag linear and non-linear models in {R}: the
      package {dlnm}},
    author = {Antonio Gasparrini and Ben Armstrong and Fabian Scheipl},
    journal = {Journal of Statistical Software},
    year = {2011},
    volume = {43},
    number = {8},
    pages = {1--20},
    doi = {10.18637/jss.v043.i08},
    url = {https://doi.org/10.18637/jss.v043.i08},
  }