To cite PTAk in publications use preferably the JSS one and the current version:
 
Package: PTAk
Version: 1.2-7
Date: 2014-08-14
Title: Principal Tensor Analysis on k modes
Author: Didier Leibovici     <didier.leibovici@nottingham.ac.uk>

Maintainer: Didier Leibovici <c3s2i@free.fr>

Depends:  tensor, tensorA
Description: A multiway method to decompose a tensor (array) of any order, as a generalisation of SVD also supporting non-identity metrics and penalisations. 2-way SVD with these extensions is also available. The package includes also some other multiway methods: PCAn (Tucker-n) and PARAFAC/CANDECOMP with these extensions.
License: GPL(>=2)
URL: http://c3s2i.free.fr/
 
 
  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
 
A BibTeX entry for LaTeX users is
 
  @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 = {Leibovici D. and Sabatier R.},
   journal = {Linear Algebra and Its Applications},
    year = {1998},
    volume = {269},
    pages = {307-329},
  }
  Leibovici D.G. (2014) PTAk: Principal Tensor Analysis on k modes, R package version 1.2-8 . http://cran.r-project.org/web/packages/PTAk/index.html.
A BibTeX entry for LaTeX users is
 
  @Manual{,
    title ={\textup{PTAk}: \textup{Principal Tensor Analysis on k modes}},
    author = {Leibovici D.G.},
    year = {2009},
    edition = {R package version 1.1-20},
    url ={http://cran.r-project.org/web/packages/PTAk/index.html},
  }
 
  Leibovici D.G. (2010) Spatio-Temporal Multiway Decompositions using Principal Tensor Analysis on k-modes: the R-package
  PTAk. Journal ofStatistical Software. 34(10): 1-34.
 
A BibTeX entry for LaTeX users is
 
 @article{Leibovici:2009:JSSOBK:v34i10,
author = "Didier G. Leibovici",
title = "Spatio-Temporal Multiway Data Decomposition Using Principal Tensor Analysis on k-Modes: The R Package PTAk",
journal = "Journal of Statistical Software",
volume = "34",
number = "10",
pages = "1--34",
day = "31",
month = "5",
year = "2010",
CODEN = "JSSOBK",
ISSN = "1548-7660",
bibdate = "2009-08-19",
URL = "http://www.jstatsoft.org/v34/i10",
accepted = "2009-08-19",
acknowledgement = "",
keywords = "",
submitted = "2008-05-08",
}
visit also http://c3s2i.free.fr or http://cgs.nottingham.ac.uk/~lgzdl