Among the many books written on the subject of economics, you should consider a few as "must-reads."

That list should include:

• Principles of Economics by Carl Menger
  • Online Version
• Human Action by Ludwig von Mises
  • Online Version
• Man, Economy, and State by Murray N. Rothbard
  • Online Version
• An Introduction to Economic Reasoning by David Gordon
  • Online Version
• Introduction to Austrian Economics by Thomas C. Taylor
  • Online Version

You can even find some of these classics online in PDF format.