P. 195, line 1

The equation should be:

$\frac{d}{dt}\left[\begin{array}{c}{\xi }_1\\ {\xi }_2\\ {\xi }_3\\ {\xi }_4\end{array}\right]=\left[\begin{array}{c}{\xi }_2\\ \frac{1}{m_1}(-b_1{\xi }_2-k_1{\xi }_1+k_2{\xi }_3-k_2{\xi }_1+b_2{\xi }_4-b_2{\xi }_2)\\ {\xi }_4\\ \frac{1}{m_2}(-k_2{\xi }_3+k_2{\xi }_1-b_2{\xi }_4+b_4{\xi }_2)\end{array}\right]$

Return to errata.