We thank all colleagues who pointed out mistakes and misprints. Any more hints are wellcome !
Known mistakes so far:
p. 6, l. -4: The volume form should be defined as $\sigma_1\wedge\ldots\wedge\sigma_n$ independent of the signature, i.e. the factor $(-1)^q$ should be discarded.
p. 127, l. 13-15: in a), there is a typo, the equation should read $(e^{2t} - x^2) + x dx/dt =0$. b) ist ok, c) should be deleted (not integrable by any elementary means).
p. 127, l. -3: Add the initial condition that $A$ should coincide with a given matrix $A_0$ for $t=0$, $A(0)=A_0$.
p. 178, l. 7/9: replace "meridian" by "parallel circle" (translation mistake).
p.223, l. 16: "and equality holds if $G$ is connected" (translation mistake).