  In a way, Weyl’s 1927 paper was programmatic in character; nearly all the topics of that paper were taken up again a year later in his  famous book (Weyl (1928)) entitled Gruppentheorie und  Quantenmechanik (The Theory of Groups and Quantum  Mechanics). The book emerged from the lecture notes taken by a  student named F. Bohnenblust of Weyl’s lectures given in Zürich  during the winter semester 1927–28. A revised edition of that  book appeared in 1931. In the preface to the first edition Weyl says: 