@techreport{oai:tsukuba.repo.nii.ac.jp:00022876,
 author = {Takano, Yuichi and Yamamoto, Yoshitsugu and 山本, 芳嗣},
 month = {May},
 title = {Metric-Preserving Reduction of Earth Mover’s Distance and its Application to Non-negative Matrix Factorization},
 year = {2008}
}