To cite multiplex/multigraph in publications use:

Rivero Ostoic JA (2020). “Algebraic Analysis of Multiple Social Networks with multiplex.” Journal of Statistical Software, 92(11), 1–41. doi: 10.18637/jss.v092.i11.

Corresponding BibTeX entry:

  @Article{,
    title = {Algebraic Analysis of Multiple Social Networks with
      {multiplex}},
    author = {J. Antonio {Rivero Ostoic}},
    journal = {Journal of Statistical Software},
    year = {2020},
    volume = {92},
    number = {11},
    pages = {1--41},
    doi = {10.18637/jss.v092.i11},
  }