To cite MatchIt in publications use:

Daniel E. Ho, Kosuke Imai, Gary King, Elizabeth A. Stuart (2009). MatchIt: Nonparametric Preprocessing for Parametric Causal Inference. Journal of Statistical Software, Forthcoming. URL http://www.jstatsoft.org/.

Corresponding BibTeX entry:

  @Article{,
    title = {{MatchIt}: Nonparametric Preprocessing for Parametric
      Causal Inference},
    author = {Daniel E. Ho and Kosuke Imai and Gary King and Elizabeth
      A. Stuart},
    journal = {Journal of Statistical Software},
    year = {2009},
    note = {Forthcoming},
    url = {http://www.jstatsoft.org/},
  }