  One of the most interesting formulas for multiple zeta values is the sum
formula proved by Granville and Zagier independently in 1990s. Many variations
and generalizations of it have been found since then. In this paper, we will
provide a uniform approach to proving these results using the regularized
double shuffle relations of Euler sums. We summarize these formulas including
many new ones with three tables in the Appendix at the end of the paper.
