SV plane waves about the X-axis

Interchangeing W₁₁ and W₃₃ wherever they occur in Eqn. (4)

$$\begin{eqnarray} W(\theta) = W_{44} C^2 + (W_{33} - \frac {(W_{13} + W_{44})^{2}}{W_{11} - W_{44}})S^{2}\end{eqnarray}$$ (6)