Well it depends, I got a SAM'S shell scripting book, a couple of years ago. I have no other programming expirience and am most effective in bash. There are many Unix shells including C as you know, and Perl in case you didnt know.
I dont know either of the two languages so I could not give you a reference to a book that allows you to excersise your perl or c skills into a c-shell, or perl-shell.
I do know one thing, it helped me a bit. I do most things in bash and dont really do any kind of migration to other shells from my normal shell. Some students at school bug me about that alot. Their teachers give them off the wall projects to transliterate and migrate data from the c-shell to the korn-shell, and the book I learned from does not cover that.
Shell programming is actually easier than C++, C, Perl and other languages, its very much like BASIC. You should not find it hard, if all else fails, goto the boring manual pages on what ever shell you want to learn about.