Calabi, Lorenzo; Ehresmann, Charles Sur les extensions de groupes topologiques.. I. (French) Zbl 0041.36102 C. R. Acad. Sci., Paris 228, 1551-1553 (1949). Page: −5 −4 −3 −2 −1 ±0 +1 +2 +3 +4 +5 Show Scanned Page Cited in 1 Document Keywords:Group theory PDFBibTeX XMLCite \textit{L. Calabi} and \textit{C. Ehresmann}, C. R. Acad. Sci., Paris 228, 1551--1553 (1949; Zbl 0041.36102)