@article{oai:ir.kagoshima-u.ac.jp:00010077,
 author = {AOYAMA, Kiwamu and 青山, 究},
 journal = {鹿児島大学理学部紀要. 数学・物理学・化学, Reports of the Faculty of Science, Kagoshima University. Mathematics, physics, chemistry},
 month = {Dec},
 pages = {23--32},
 title = {A Note on Definable Subsets of Nk},
 volume = {26},
 year = {1993}
}