To cite flashClust in publications use:

Peter Langfelder, Steve Horvath (2012). Fast R Functions for Robust Correlations and Hierarchical Clustering. Journal of Statistical Software, 46(11), 1-17. URL http://www.jstatsoft.org/v46/i11/.

Corresponding BibTeX entry:

  @Article{,
    title = {Fast {R} Functions for Robust Correlations and
      Hierarchical Clustering},
    author = {Peter Langfelder and Steve Horvath},
    journal = {Journal of Statistical Software},
    year = {2012},
    volume = {46},
    number = {11},
    pages = {1--17},
    url = {http://www.jstatsoft.org/v46/i11/},
  }