C Reference Books -- feel free to suggest your favorite to add to this list
Programmming in C (3ed) by Stephen G. Kochan
Sams Publishing, 2005, ISBN 0-672-32666-3
Secure Coding in C and C++ by Robert C Seacord
Addison Wesley Publishing, 2006, ISBN 0-321-33572-4
The C Answer Book (2ed) by Clovis L. Tondo & Scott E. Gimple -- The answers to all the exercises in K & R Prentice Hall Publishing, 1989, ISBN 0-13-109653-2
Unix Power Tools (3ed) by Powers, O'Reilly & Loukides
-- Everything you wanted to know to work in the Unix environment O'Reilly, 2003, ISBN 0-596-003330-7