@article{oai:tsukuba.repo.nii.ac.jp:00016186,
 author = {Takano, Mitio},
 issue = {2},
 journal = {Tsukuba Journal of Mathematics},
 month = {Dec},
 pages = {349--351},
 title = {Existence of the least and the greatest elements of a subset of the Lindenbaum algebra},
 volume = {9},
 year = {1985}
}