To cite mixexp in publications use:

  John Lawson, Cameron Willden (2016). Mixture Experiments in R Using
  mixexp. Journal of Statistical Software, Code Snippets, 72(2), 1-20.
  doi:10.18637/jss.v072.c02

A BibTeX entry for LaTeX users is

  @Article{,
    title = {Mixture Experiments in {R} Using {mixexp}},
    author = {John Lawson and Cameron Willden},
    journal = {Journal of Statistical Software, Code Snippets},
    year = {2016},
    volume = {72},
    number = {2},
    pages = {1--20},
    doi = {10.18637/jss.v072.c02},
  }