To cite HarmonicRegression in publications use:

Sarah Lueck, Kevin Thurley, Paul F. Thaben, Paal O. Westermark (2015). Rhythmic degradation explains and unifies circadian transcriptome and proteome data. Cell Reports, 9, 741--751. URL http://www.ncbi.nlm.nih.gov/pubmed/25373909.

Corresponding BibTeX entry:

  @Article{,
    title = {Rhythmic degradation explains and unifies circadian
      transcriptome and proteome data.},
    author = {Sarah Lueck and Kevin Thurley and Paul F. Thaben and Paal
      O. Westermark},
    journal = {Cell Reports},
    year = {2014},
    volume = {9},
    pages = {741--751},
    url = {http://www.ncbi.nlm.nih.gov/pubmed/25373909},
  }