Do any one know how can I find second hand books?

[armstrong800]

Hello, every one, I wonder do any of you know how to find used books?

I need some text books in a hurry. But I am so poor that I can not afford the price of new books.

This is the ISBN list of the books I need:

1. 0766811603 Digital Design With Cpld Application

2. 0131111388 Electronics Fundamentals: Circuits, Devices, and

Applications

3. 0536750424 Fundamental Math Essentials - Custom Publication

4. 0886202558 Soldering Techniques For Electronic Assemblers

Any one who has any of these used books or know where can I find them please tell me!

Thanks a lot!