What are good science, history, computer science, math, and robotics books

and/or encyclopedias? I am starting to compete state and nation wide next year, and would like to improve/consolidate prior knowledge before then, during next year, and after. I need some suggestions for general fact/knowledge books and/or encyclopedias in these areas:
1) General science (biology, chemistry, physics, astronomy, etc.) 2) History (US history, world history, etc.) 3) Computer Science (learning programming and general knowledge) 4) Math (Practice problems and examples: some geometry, precalculus, and calculus) 5) Robotics/Mechanics (building and understanding components).

Suggestions??
-Thank you