Primitive of Reciprocal of x by x cubed plus a cubed

Theorem

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