@article{SugYamBunSuzKanKaw11Direct,
    author = {Sugiyama, Masashi and Yamada, Makoto and von B\"{u}nau, Paul and Suzuki, Taiji and Kanamori, Takafumi and Kawanabe, Motoaki},
    title = "Direct density-ratio estimation with dimensionality reduction via least-squares hetero-distributional subspace search",
    journal = "Neural Networks",
    volume = "24",
    number = "2",
    pages = "183-198",
    year = "2011",
    issn = "0893-6080",
    doi = "10.1016/j.neunet.2010.10.005"
}