To cite package imbalance in publications use:

Cordón I, García S, Fernández A, Herrera F (2018). “Imbalance: Oversampling algorithms for imbalanced classification in R.” Knowledge-Based Systems, 161, 329-341. https://doi.org/10.1016/j.knosys.2018.07.035.

Corresponding BibTeX entry:

  @Article{,
    title = {Imbalance: Oversampling algorithms for imbalanced
      classification in R},
    author = {Ignacio Cordón and Salvador García and Alberto Fernández
      and Francisco Herrera},
    month = {12},
    year = {2018},
    pages = {329-341},
    journal = {Knowledge-Based Systems},
    volume = {161},
    url = {https://doi.org/10.1016/j.knosys.2018.07.035},
  }