Primitive of Reciprocal of x squared by x squared minus a squared squared

Theorem

 * $\displaystyle \int \frac {\mathrm d x} {x^2 \left({x^2 - a^2}\right)^2} = \frac {-1} {a^4 x} - \frac x {2 a^4 \left({x^2 - a^2}\right)} + \frac 3 {4 a^5} \ln \left({\frac {x + a} {x - a} }\right) + C$

for $x^2 > a^2$.