To cite package 'pan' in publications use:

Zhao JH, Schafer JL (2018). pan: Multiple imputation for multivariate panel or clustered data. R package version 1.6.

Corresponding BibTeX entry:

  @Manual{,
    title = {pan: Multiple imputation for multivariate panel or
      clustered data},
    author = {Jing Hua Zhao and Joseph L. Schafer},
    year = {2018},
    note = {R package version 1.6},
  }