Primitive of Reciprocal of x by x fourth minus a fourth

Theorem

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