To cite mice in publications use:

  Stef van Buuren, Karin Groothuis-Oudshoorn (2011). mice: Multivariate
  Imputation by Chained Equations in R. Journal of Statistical
  Software, 45(3), 1-67. DOI 10.18637/jss.v045.i03.

A BibTeX entry for LaTeX users is

  @Article{,
    title = {{mice}: Multivariate Imputation by Chained Equations in R},
    author = {Stef {van Buuren} and Karin Groothuis-Oudshoorn},
    journal = {Journal of Statistical Software},
    year = {2011},
    volume = {45},
    number = {3},
    pages = {1-67},
    doi = {10.18637/jss.v045.i03},
  }