Boundary Value Problems and Hardy Spaces for Elliptic Systems with Block Structure

On Necessary and Sufficient Conditions for L^p-estimates of Riesz Transforms Associated to Elliptic Operators on R^n and Related Estimates (Memoirs of the American Mathematical Society)

Heat kernels and analysis on manifolds, graphs, and metric spaces

On necessary and sufficient conditions for Lp-estimates of Riesz transforms associated to elliptic operators on Rn and related estimates