  The two-loop three-gluon vertex is calculated in an arbitrary covariant
gauge, in the limit when one of the external momenta vanishes. The differential
Ward-Slavnov-Taylor (WST) identity related to this limit is discussed, and the
relevant results for the ghost-gluon vertex and two-point functions are
obtained. Together with the differential WST identity, they provide another
independent way for calculating the three-gluon vertex. The renormalization of
the results obtained is also presented.
