Here are a couple books:
Standard C books:
1) C Primer Plus (Revised Edition) Howard Sams Books <VERY GOOD>
2) Writing Solid Code, Microsoft Press <VERY GOOD>
3) Code Complete, Microsoft <VERY GOOD>
Amiga specific:
1) The RKM books, Commodore <NEED THESE>
There are other Amiga specific books, but they are out dated.