To cite ddalpha in publications use:

Pokotylo O, Mozharovskyi P, Dyckerhoff R (2019). “Depth and Depth-Based Classification with R Package ddalpha.” Journal of Statistical Software, 91(5), 1–46. doi: 10.18637/jss.v091.i05.

Corresponding BibTeX entry:

  @Article{,
    title = {Depth and Depth-Based Classification with {R} Package
      {ddalpha}},
    author = {Oleksii Pokotylo and Pavlo Mozharovskyi and Rainer
      Dyckerhoff},
    journal = {Journal of Statistical Software},
    year = {2019},
    volume = {91},
    number = {5},
    pages = {1--46},
    doi = {10.18637/jss.v091.i05},
  }