@conference{
    PNMFICFE,
    author = "Yuan, Zhijian and Oja, Erkki",
    publisher = "Springer",
    title = "Projective nonnegative matrix factorization for image compression and feature extraction",
    timestamp = "2008.12.01",
    booktitle = "14th Scandinavian Conference on Image Analysis",
    volume = "3540",
    year = "2005",
    flaggs = "RAE",
    pages = "333-342"
}