To cite ade4 in publications use one these references:

Dray, S. and Dufour, A.B. (2007): The ade4 package: implementing the duality diagram for ecologists. Journal of Statistical Software. 22(4): 1-20.
Chessel, D. and Dufour, A.B. and Thioulouse, J. (2004): The ade4 package-I- One-table methods. R News. 4: 5-10.
Dray, S. and Dufour, A.B. and Chessel, D. (2007): The ade4 package-II: Two-table and K-table methods. R News. 7(2): 47-52.

Corresponding BibTeX entries:

  @Article{,
    title = {The ade4 package: implementing the duality diagram for
      ecologists},
    author = {S. Dray and A.B. Dufour},
    journal = {Journal of Statistical Software},
    year = {2007},
    volume = {22},
    pages = {1-20},
    number = {4},
  }
  @Article{,
    title = {The ade4 package-{I}- {O}ne-table methods},
    author = {D. Chessel and A.B. Dufour and J. Thioulouse},
    journal = {R News},
    year = {2004},
    volume = {4},
    pages = {5-10},
  }
  @Article{,
    title = {The ade4 package-{II}: {T}wo-table and {K}-table
      methods.},
    author = {S. Dray and A.B. Dufour and D. Chessel},
    journal = {R News},
    year = {2007},
    volume = {7},
    number = {2},
    pages = {47-52},
  }