To cite trustOptim in publications use:

Michael Braun (2014). trustOptim: An R Package for Trust Region Optimization with Sparse Hessians. Journal of Statistical Software, 60(4), 1-16. URL http://www.jstatsoft.org/v60/i04/.

Corresponding BibTeX entry:

  @Article{,
    title = {{trustOptim}: An {R} Package for Trust Region Optimization
      with Sparse Hessians},
    author = {Michael Braun},
    journal = {Journal of Statistical Software},
    year = {2014},
    volume = {60},
    number = {4},
    pages = {1--16},
    url = {http://www.jstatsoft.org/v60/i04/},
  }