Reference:
  Author: Renaud Gaujoux and Cathal Seoighe
  Title: "A flexible R package for nonnegative matrix factorization"
  Journal: BMC Bioinformatics
  Year: 2010
  Volume: 11
  Number: 1
  Pages: 367
  DOI: 10.1186/1471-2105-11-367
  PMID: 20598126
  URL: http://www.biomedcentral.com/1471-2105/11/367
  eprint: http://bmcbioinformatics.biomedcentral.com/track/pdf/10.1186/1471-2105-11-367
  issn: 1471-2105
