To cite package flexclust in publications use:

Friedrich Leisch. A Toolbox for K-Centroids Cluster Analysis. Computational Statistics and Data Analysis, 51 (2), 526-544, 2006.

Visualization methods are explained in:

Friedrich Leisch. Neighborhood graphs, stripes and shadow plots for cluster visualization. Statistics and Computing, 20 (4), 457-469, 2010.

Group constraints are explained in:

Friedrich Leisch and Bettina Gruen. Extending standard cluster algorithms to allow for group constraints. In Alfredo Rizzi and Maurizio Vichi, editors, Compstat 2006-Proceedings in Computational Statistics, pages 885-892. Physica Verlag, Heidelberg, Germany, 2006.

Function qtclust() is explained in:

Theresa Scharl and Friedrich Leisch. The Stochastic QT-clust Algorithm: Evaluation of Stability and Variance on Time-course Microarray Data. In Alfredo Rizzi and Maurizio Vichi, editors, Compstat 2006-Proceedings in Computational Statistics, pages 1015-1022. Physica Verlag, Heidelberg, Germany, 2006.

Using flexclust for market segmentation is explained in:

Sara Dolnicar, Bettina Gruen, and Friedrich Leisch. Market Segmentation Analysis --- Understanding It, Doing It, and Making It Useful. Management for Professionals. Springer, Singapore, 2018.<doi:10.1007/978-981-10-8818-6>

Papers are available from https://homepage.boku.ac.at/leisch/papers/fl-publications.html

Corresponding BibTeX entries:

  @Article{,
    author = {Friedrich Leisch},
    title = {A Toolbox for K-Centroids Cluster Analysis},
    journal = {Computational Statistics and Data Analysis},
    year = {2006},
    volume = {51},
    number = {2},
    pages = {526--544},
  }

  @Article{,
    author = {Friedrich Leisch},
    title = {Neighborhood graphs, stripes and shadow plots for cluster
      visualization},
    journal = {Statistics and Computing},
    year = {2010},
    volume = {20},
    issue = {4},
    pages = {457--469},
    doi = {10.1007/s11222-009-9137-8},
  }

  @InProceedings{,
    author = {Friedrich Leisch and Bettina Gruen},
    title = {Extending Standard Cluster Algorithms to Allow for Group
      Constraints},
    booktitle = {Compstat 2006---Proceedings in Computational
      Statistics},
    pages = {885--892},
    editor = {Alfredo Rizzi and Maurizio Vichi},
    publisher = {Physica Verlag, Heidelberg, Germany},
    isbn = {3-7908-1708-2},
    year = {2006},
  }

  @InProceedings{,
    author = {Theresa Scharl and Friedrich Leisch},
    title = {The Stochastic QT--clust Algorithm: Evaluation of
      Stability and Variance on Time--course Microarray Data},
    booktitle = {Compstat 2006---Proceedings in Computational
      Statistics},
    pages = {1015--1022},
    editor = {Alfredo Rizzi and Maurizio Vichi},
    publisher = {Physica Verlag, Heidelberg, Germany},
    isbn = {3-7908-1708-2},
    year = {2006},
  }

  @Book{,
    author = {Sara Dolnicar and Bettina Gruen and Friedrich Leisch},
    title = {Market Segmentation Analysis --- Understanding It, Doing
      It, and Making It Useful},
    publisher = {Springer},
    year = {2018},
    address = {Singapore},
    doi = {10.1007/978-981-10-8818-6},
  }