The C programming Language by Kernighan and Ritchie is a very good introductory book for learning C. But it is also a very concentrated book and every word has to be read with care as it contains a lot of details.
If you do not have any experience in programming, I suggest you first read the book by Balagurusamy and then K & R.
I don't recommend Let us C because it contains a lot of stuff specific to Windows which is not needed for beginners.
