ON SEMI-GROUPS OF OPERATOR TRANSFORMATIONS Authors A. Bleyer PDF How to Cite Bleyer, A. “ON SEMI-GROUPS OF OPERATOR TRANSFORMATIONS”, Periodica Polytechnica Electrical Engineering, 21(2), pp. 175–196, 1977. More Citation Formats Periodica Polytechnica Numbered ACM ABNT Chicago Harvard IEEE Vancouver Download Citation Endnote/Zotero/Mendeley (RIS) BibTeX Issue Vol. 21 No. 2 (1977) Section Articles