  Recurrence relations derived via the Chetyrkin--Tkachov method of integration
by parts are applied to reduce scalar three-loop bubble (vacuum) diagrams with
a mass to a limited number of master integrals. The reduction is implemented as
a package of computer programs for analytic evaluation in FORM. The algorithms
are applicable to diagrams with any integer powers on the lines in an arbitrary
dimension. A physical application is the evaluation of the three-loop QCD
correction to the electroweak rho parameter.
