To cite pseval in publications use:

Michael C. Sachs and Erin E. Gabriel (2016). pseval: Methods for Evaluating Principal Surrogates of Treatment Response. R package version 1.3.0.

Corresponding BibTeX entry:

  @Manual{,
    title = {pseval: Methods for Evaluating Principal Surrogates of
      Treatment Response},
    author = {Michael C. Sachs and Erin E. Gabriel},
    year = {2016},
    note = {R package version 1.3.0},
  }