Ward, Morgan The closure operators of a lattice. (English) Zbl 0063.08179 Ann. Math. (2) 43, 191-196 (1942). Not reviewed Cited in 34 Documents PDF BibTeX XML Cite \textit{M. Ward}, Ann. Math. (2) 43, 191--196 (1942; Zbl 0063.08179) Full Text: DOI OpenURL