To cite the package 'ppclust' in publications use:

Cebeci, Z. (2018), Comparison of internal validity indices for fuzzy clustering. Journal of Agricultural Informatics, 10(2):1-14<doi:10.17700/jai.2019.10.2.537>

Corresponding BibTeX entry:

  @Article{,
    title = {Comparison of Internal Validity Indices for Fuzzy
      Clustering},
    author = {Zeynel Cebeci},
    journal = {Journal of Agricultural Informatics},
    year = {2019},
    vol = {10},
    number = {2},
    pages = {1-14},
    doi = {10.17700/jai.2019.10.2.537},
  }