To cite hmi in publications use:

Speidel M, Drechsler J, Jolani S (2020). “The R Package hmi: A Convenient Tool for Hierarchical Multiple Imputation and Beyond.” Journal of Statistical Software, 95(9), 1–48. doi: 10.18637/jss.v095.i09.

Corresponding BibTeX entry:

  @Article{,
    title = {The {R} Package {hmi}: A Convenient Tool for Hierarchical
      Multiple Imputation and Beyond},
    author = {Matthias Speidel and J\"org Drechsler and Shahab Jolani},
    journal = {Journal of Statistical Software},
    year = {2020},
    volume = {95},
    number = {9},
    pages = {1--48},
    doi = {10.18637/jss.v095.i09},
  }