@article{oai:tsukuba.repo.nii.ac.jp:00015704,
 author = {Yasugi, Mariko and Tsujii, Yoshiki and Mori, Takakazu},
 issue = {1},
 journal = {Tsukuba Journal of Mathematics},
 month = {Jun},
 pages = {251--265},
 title = {A metatheory of nonstandard analysis},
 volume = {17},
 year = {1993}
}