Russell, S., and Norvig, P., (2002). Artificial Intelligence: A Modern Approach. Prentice Hall, 2nd edition.
Nilsson, N., (1998). AI: A New Synthesis. Morgan Kauffman. A new book from one of the most important classical AI authors.
Pearl, J., (1984). Heuristics: Intelligent Search Strategies for Computer Problem-Solving. Addison Wesley. A very interesting and unconventional book discussing a large number of interesting questions and deep issues connected with heuristics used in classical AI. Some prior experience with AI search methods is probably useful before reading this book.
Pearl, J., (2000). Causality: Models, Reasoning and Inference. Cambridge, UK: Cambridge University Press.
Saygin, A., Cicekli, I., and Akman, V., (2000). Turing Test: 50 Years Later. Minds and Machines, 10(4):463-518.
Schalkoff, R. J., (1990). Artificial Intelligence: An Engineering Approach. New York, USA: McGraw-Hill.
Sutton, R. S., and Barto, A. G., (1998). Reinforcement Learning. Cambridge, Mass.: MIT Press. The standard reference for reinforcement learning.
Winston, P. H., (1993). Artificial Intelligence. Addison-Wesley. Classical book, perhaps a bit dated.