1. [ACG+03]_G. Ausiello, P. Crescenzi, G. Gambosi, V. Kann, M. Marchetti-Spaccamela, and M. Protasi. Complexity and Approximation. Springer-Verlag, second edition, 2003.
2. E. Allender and L. Hemachandra. Lower bounds for the low hierarchy. Journal of the ACM, 39(1):234–251, 1992.
3. [AHH+93]_V. Arvind, Y. Han, L. Hemachandra, J. Köbler, A. Lozano, M. Mundhenk, M. Ogiwara, U. Schöning, R. Silvestri, and T. Thierauf. Reductions to sets of low information content. In K. Ambos-Spies, S. Homer, and U. Schöning, editors, Complexity Theory, pages 1–45. Cambridge University Press, 1993.
4. [ALM+98]_S. Arora, C. Lund, R. Motwani, M. Sudan, and M. Szegedy. Proof verification and intractability of approximation problems. Journal of the ACM, 45(3):501–555, May 1998.
5. L. Adleman and K. Manders. Reducibility, randomness, and intractibility. In Proceedings of the 9th ACM Symposium on Theory of Computing, pages 151–153. ACM Press, 1977.