To cite the 'mnormt' package in publications use:

Azzalini, A. and Genz, A. (2022). The R package 'mnormt': The multivariate normal and 't' distributions (version 2.1.1). URL http://azzalini.stat.unipd.it/SW/Pkg-mnormt/

Corresponding BibTeX entry:

  @Manual{,
    title = {The {R} package \texttt{mnormt}: The multivariate normal
      and $t$ distributions (version 2.1.1)},
    author = {Adelchi Azzalini and Alan Genz},
    year = {2022},
    url = {http://azzalini.stat.unipd.it/SW/Pkg-mnormt/},
  }