P. 206, lines 4 and 7

The right expression on line 4 should be:

${\hat{\xi }}^1=\left[\begin{array}{c}{\hat{\xi }}_1^1\\ {\hat{\xi }}_2^1\end{array}\right]=\left[\begin{array}{c}1\\ -i\end{array}\right].$

and the right expression on line 7 should be:

${\hat{\xi }}^2=\left[\begin{array}{c}{\hat{\xi }}_1^2\\ {\hat{\xi }}_2^2\end{array}\right]=\left[\begin{array}{c}1\\ i\end{array}\right].$

Return to errata.