To cite the package 'ppclust' in publications use:

Cebeci Z (2019). “Comparison of Internal Validity Indices for Fuzzy Clustering.” Journal of Agricultural Informatics, 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},
  }