https://9lib.org/document/yevwxoj4-allmapsareassumedtobe-andlinearmapmeans-allobjectsconsideredherearefirstofall-algebrasandhomomorpismsareassumedtobeunital-denotessomefixedunitalandcommutativering-algebrasareunitalassociative-firstordercalculiwithvaluesinright-universalbimodules.html