To cite package 'btergm' in publications use:

Leifeld, Philip, Skyler J. Cranmer and Bruce A. Desmarais (2016). btergm. Temporal Exponential Random Graph Models by Bootstrapped Pseudolikelihood. R package version 1.8.1.

Corresponding BibTeX entry:

  @Manual{,
    title = {btergm: Temporal Exponential Random Graph Models by
      Bootstrapped Pseudolikelihood},
    author = {Philip Leifeld and Skyler J. Cranmer and Bruce A.
      Desmarais},
    year = {2016},
    note = {R package version 1.8.1},
    url = {https://CRAN.R-project.org/package=btergm},
  }