  In higher order calculations a number of new technical problems arise: one
needs diagrams in arbitrary dimension in order to obtain their needed
$\epsilon$-expansion, zero Gram determinants appear, renormalization produces
diagrams with `dots' on the lines, i.e. higher order powers of scalar
propagators. All these problems cannot be accessed by the `standard'
Passarino-Veltman approach: there is not available what is needed for higher
loops. We demonstrate our method of how to solve these problems.
