To cite package ‘chngpt’ in publications use:

  Fong Y, Huang Y, Gilbert P, Permar S (2017). _chngpt: threshold
  regression model estimation and inference_, volume
  DOI:10.1186/s12859-017-1863-x.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {chngpt: threshold regression model estimation and inference},
    author = {Youyi Fong and Ying Huang and Peter Gilbert and Sallie Permar},
    journal = {BMC Bioinformatics},
    year = {2017},
    volume = {DOI:10.1186/s12859-017-1863-x},
  }