https://9lib.org/document/y96r858j-hochschildhomologygroupisnaturallyisomorphictoafamiliarfreeabeliangroupemployedinnielsentheory-hochschildhomologygroup-parameternielsenfixedpointtheoryisobstructedbyanelementofan-andthevariousreidemeistertorsionsassociatedwithasuspensionflow-theoreticobstr.html