To cite nlsem in publications use:

Nora Umbach, Katharina Naumann, Holger Brandt, Augustin Kelava (2017). Fitting Nonlinear Structural Equation Models in R with Package nlsem. Journal of Statistical Software, 77(7), 1-20.<doi:10.18637/jss.v077.i07>

Corresponding BibTeX entry:

  @Article{,
    title = {Fitting Nonlinear Structural Equation Models in {R} with
      Package {nlsem}},
    author = {Nora Umbach and Katharina Naumann and Holger Brandt and
      Augustin Kelava},
    journal = {Journal of Statistical Software},
    year = {2017},
    volume = {77},
    number = {7},
    pages = {1--20},
    doi = {10.18637/jss.v077.i07},
  }