C Book Recommendations

These books are recommended to improve your C knowledge, for reference, or for learning material.

C: A Reference Manual This is a concise reference book, explaining syntax and conceptual information in sufficient detail to aid learning. But this is not a tutorial book. I would advise purchase of this book along with a tutorial book, if you are learning C.
An Introduction to ANSI C on Unix This is an good book for C programming under UNIX.
Sams Teach Yourself C in 21 Days I have an earlier edition of this book, which has good introductory material. This is a tutorial style book, and therefore I would recommend it for learning the C language.