@article{oai:repository.dl.itc.u-tokyo.ac.jp:00041056,
 author = {Niiro, Fumio|Sawashima  Ikuko},
 journal = {Scientific papers of the College of General Education, University of Tokyo},
 month = {},
 note = {application/pdf},
 pages = {93--98},
 title = {On a Set Including the Spectra of Positive Operators},
 volume = {23},
 year = {1973}
}