To cite nmfem in publications use:

Léna Carel, Pierre Alquier (2017). Simultaneous Dimension Reduction and Clustering via the NMF-EM Algorithm. URL https://arxiv.org/pdf/1709.03346.pdf.

Corresponding BibTeX entry:

  @Unpublished{,
    title = {Simultaneous Dimension Reduction and Clustering via the
      NMF-EM Algorithm},
    author = {Léna Carel and Pierre Alquier},
    year = {2017},
    url = {https://arxiv.org/pdf/1709.03346.pdf},
    note = {Submitted on 2017/11/02},
  }