On Quantum Versions of the Yao Principle. - Mart de Graaf; Ronald de Wolf (STACS, 2002)

Comparing EQP and MOD_{p^k}P using Polynomial Degree Lower Bounds - Mart de Graaf; Paul Valiant (CoRR, 2002)

Polynomial Representations of Symmetric Partial Boolean Functions. - Mart de Graaf; Paul Valiant (SIAM J. Discret. Math., 2005)