1. Riis, S.: A complexity gap for tree-resolution. Computational Complexity 10, 179–209 (2001)
2. Ben-Sasson, E., Impagliazzo, R., Wigderson, A.: Near-optimal separation of general and tree-like resolution. Combinatorica (to appear)
3. Bonet, M., Galesi, N.: A study of proof search algorithms for resolution and polynomial calculus. In: Proceedings of the 40th IEEE Symposium on Foundations of Computer Science, IEEE, Los Alamitos (1999)
4. Krajicek, J.: Combinatorics of first order structures and propositional proof systems (2001)
5. Dantchev, S., Riis, S.: Tree resolution proofs of the weak pigeon-hole principle. In: Proceedings of the 16th annual IEEE Conference on Comutational Complexity, IEEE, Los Alamitos (2001)