P. 662, line 8

The equation should be

$X(s)=A(\mathrm{Im}\left(G_p\left(i\omega \right)\right)\frac{\omega }{s^2+{\omega }^2}+\mathrm{Re}\left(G_p\left(i\omega \right)\right)\frac{s}{s^2+{\omega }^2})+\text{other stable terms.}$

Return to errata.