To cite DMwR2 in publications use:

Torgo L (2016). Data Mining with R, learning with case studies, 2nd edition. Chapman and Hall/CRC. http://ltorgo.github.io/DMwR2.

Corresponding BibTeX entry:

  @Book{,
    title = {Data Mining with R, learning with case studies, 2nd
      edition},
    author = {L. Torgo},
    publisher = {Chapman and Hall/CRC},
    year = {2016},
    url = {http://ltorgo.github.io/DMwR2},
  }