To cite RcppEigen in publications use:

Douglas Bates, Dirk Eddelbuettel (2013). Fast and Elegant Numerical Linear Algebra Using the RcppEigen Package. Journal of Statistical Software, 52(5), 1-24. URL http://www.jstatsoft.org/v52/i05/.

Corresponding BibTeX entry:

  @Article{,
    title = {Fast and Elegant Numerical Linear Algebra Using the
      {RcppEigen} Package},
    author = {Douglas Bates and Dirk Eddelbuettel},
    journal = {Journal of Statistical Software},
    year = {2013},
    volume = {52},
    number = {5},
    pages = {1--24},
    url = {http://www.jstatsoft.org/v52/i05/},
  }