Fujiwara, Tsuyoshi Characterization of axiomatic classes of groupoids closed under identity element extensions. (English) Zbl 0523.20035 Math. Jap. 28, 633-637 (1983). MSC: 20M05 PDFBibTeX XMLCite \textit{T. Fujiwara}, Math. Japon. 28, 633--637 (1983; Zbl 0523.20035)
Roman’kov, V. A. Universal theory of nilpotent groups. (English) Zbl 0425.20027 Math. Notes 25, 253-258 (1979). MSC: 20F10 20F18 20A15 03B30 03B10 PDFBibTeX XMLCite \textit{V. A. Roman'kov}, Math. Notes 25, 253--258 (1979; Zbl 0425.20027) Full Text: DOI
Roman’kov, V. A. Universal theory of nilpotent groups. (Russian) Zbl 0419.20031 Mat. Zametki 25, 487-495 (1979). MSC: 20F10 20F18 20A15 03B30 03B10 PDFBibTeX XMLCite \textit{V. A. Roman'kov}, Mat. Zametki 25, 487--495 (1979; Zbl 0419.20031)