http://www.referee.com/books/books/bfbrd05.htm NASO price $13.55
http://www.honigs.com/detail.asp?Cat=1&Sub=123&Item=301 $14.95
It is a good book. I didn't purchase the 2005 version because I don't work too many college games (yet) but the way the book is written adds clarity to the different codes. I strongly encourage anyone who works both to get this book.
Also, I just purchased Redding's Study Guide for NFHS rules. I think this is the first year it was published. I know they have published the college version for a while, and both books are another great study tool.
http://www.honigs.com/detail.asp?Cat=1&Sub=123&Item=561
http://www.honigs.com/detail.asp?Cat=1&Sub=123&Item=560