@article{oai:tsukuba.repo.nii.ac.jp:00017273,
 author = {Ikeda, Kazuma},
 issue = {2},
 journal = {Tsukuba Journal of Mathematics},
 month = {Oct},
 pages = {285--304},
 title = {A normal form for arithmetical derivations implying the ω-consistency of arithmetic},
 volume = {21},
 year = {1997}
}