@techreport{oai:tsukuba.repo.nii.ac.jp:00050002,
 author = {五十嵐, 岳 and IGARASHI, Gaku},
 month = {May},
 title = {Nonparametric direct density ratio estimation using beta kernel},
 year = {2019},
 yomi = {イガラシ, ガク}
}