I'm looking for good books on concurrent programming in C in the Unix environment. They need to cover classic concurrency, Unix multi-processing, and POSIX thread. Most of the books I have found are not for C or Unix. Keep in mind that I am not expecting one book to cover all of that though it would be great if such a book existed.
The best book that I have found so far is Programming with POSIX Threads but it only covers threads. This is great but I need more information on concurrency and multi-processing. I am also interested in concurrency issues in databases and architecture.
I am looking for books that are particular to C and Unix, but if you know of a good book that teaches the fundamentals of concurrency really well I would be interested in that also even if it is not in C or for Unix.
Ebooks and online articles are also appreciated.