To cite dbscan in publications use:

Hahsler M, Piekenbrock M, Doran D (2019). “dbscan: Fast Density-Based Clustering with R.” Journal of Statistical Software, 91(1), 1–30. doi: 10.18637/jss.v091.i01.

Corresponding BibTeX entry:

  @Article{,
    title = {{dbscan}: Fast Density-Based Clustering with {R}},
    author = {Michael Hahsler and Matthew Piekenbrock and Derek Doran},
    journal = {Journal of Statistical Software},
    year = {2019},
    volume = {91},
    number = {1},
    pages = {1--30},
    doi = {10.18637/jss.v091.i01},
  }