To cite PTAk in publications use preferably the JSS one and the current version:

Leibovici, D. and Sabatier, R.(1998)A Singular Value Decomposition of k-Way Array for a Principal Component Analysis of Multiway Data, PTA-k. Linear Algebra and its Applications, 269:307-329
Leibovici D.G. (2012) PTAk: Principal Tensor Analysis on k modes, R package version 1.2-6 . http://cran.r-project.org/web/packages/PTAk/index.html.
Didier G. Leibovici (2010). Spatio-Temporal Multiway Decompositions Using Principal Tensor Analysis on k-Modes: The R Package PTAk. Journal of Statistical Software, 34(10), 1-34. URL http://www.jstatsoft.org/v34/i10/.

visit also http://c3s2i.free.fr or http://cgs.nottingham.ac.uk/~lgzdl

Corresponding BibTeX entries:

  @Article{,
    title = {\textup{A Singular Value Decomposition of \textit{k}-Way
      Array for a Principal Component Analysis of Multiway Data,
      \textsc{PTA}-\textit{k}}},
    author = {D. Leibovici and R. Sabatier},
    journal = {Linear Algebra and Its Applications},
    year = {1998},
    volume = {269},
    pages = {307-329},
  }
  @Manual{,
    title = {\textup{PTAk}: \textup{Principal Tensor Analysis on k
      modes}},
    author = {Leibovici D.G.},
    year = {2012},
    edition = {R package version 1.2-6},
    url = {http://cran.r-project.org/web/packages/PTAk/index.html},
  }
  @Article{,
    title = {\textup{Spatio-Temporal Multiway Decompositions using
      Principal Tensor Analysis on k-modes: the \textsc{R}-package
      \textsc{PTAk}}},
    author = {Didier G. Leibovici},
    journal = {Journal of Statistical Software},
    year = {2010},
    volume = {34},
    number = {10},
    pages = {1--34},
    url = {http://www.jstatsoft.org/v34/i10/},
  }