To cite adespatial in publications use:

Dray S, Bauman D, Blanchet G, Borcard D, Clappe S, Guénard G, Jombart T, Larocque G, Legendre P, Madi N, Wagner HH (2022). adespatial: Multivariate Multiscale Spatial Analysis. R package version 0.3-19, https://CRAN.R-project.org/package=adespatial.

When using constr.hclust() please use:

Guénard G, Legendre P (2022). “Hierarchical Clustering with Contiguity Constraint in R.” Journal of Statistical Software, 103(7), 1–26. doi:10.18637/jss.v103.i07.

Corresponding BibTeX entries:

  @Manual{,
    title = {{adespatial}: Multivariate Multiscale Spatial Analysis},
    author = {St{\'e}phane Dray and David Bauman and Guillaume Blanchet
      and Daniel Borcard and Sylvie Clappe and Guillaume Gu{\'e}nard
      and Thibaut Jombart and Guillaume Larocque and Pierre Legendre
      and Naima Madi and Helene H Wagner},
    year = {2022},
    note = {R package version 0.3-19},
    url = {https://CRAN.R-project.org/package=adespatial},
  }

  @Article{,
    title = {Hierarchical Clustering with Contiguity Constraint in
      {R}},
    author = {Guillaume Gu{\'e}nard and Pierre Legendre},
    journal = {Journal of Statistical Software},
    year = {2022},
    volume = {103},
    number = {7},
    pages = {1--26},
    doi = {10.18637/jss.v103.i07},
  }