Equation (3.83): The statement should be that both these expressions equal zero.
Equation (6.7): The index "i" should be replaced by the index "3".
Equation (7.64): In the left equation, a minus should be inserted after the equal sign.
Equation (7.65): There should be a plus rather than a minus in front of the second cubic term on the r.h. side.
I am grateful to Björn Friedrich for noticing the errors above.
Further corrections are highly welcome!