Kim, K. H.; Roush, F. W. Enumeration of certain words. (English) Zbl 0442.20048 Acta Cybern. 4, No. 4, 383-387 (1980). MSC: 20M05 05A15 PDFBibTeX XMLCite \textit{K. H. Kim} and \textit{F. W. Roush}, Acta Cybern. 4, No. 4, 383--387 (1980; Zbl 0442.20048) Full Text: Link
Kim, K. H.; Roush, F. W. Schützenberger’s monoids. (English) Zbl 0421.20030 Acta Cybern. 4, 269-272 (1979). MSC: 20M10 PDFBibTeX XMLCite \textit{K. H. Kim} and \textit{F. W. Roush}, Acta Cybern. 4, 269--272 (1979; Zbl 0421.20030)