Whyburn, Gordon T. Directed families of sets and closedness of functions. (English) Zbl 0139.16204 Proc. Natl. Acad. Sci. USA 54, 688-692 (1965). Page: −5 −4 −3 −2 −1 ±0 +1 +2 +3 +4 +5 Show Scanned Page Cited in 12 Documents Keywords:topology PDFBibTeX XMLCite \textit{G. T. Whyburn}, Proc. Natl. Acad. Sci. USA 54, 688--692 (1965; Zbl 0139.16204) Full Text: DOI Link