Hello, I’m new in the real time systems world and I would like to learn as much as possible. I have a couple of books and I wish you would add (or remove) books to the list. Thank you very much 
“Real-Time System Design and Analysis”, Phillip A. Laplante, IEEE press
“Modelling and Verification of Real-Time systems Using Timed Automata: Theory and Practice”, Paul Pettersson.
I’ve used these two ones and they’re pretty useful. The info and the prices have been taken from the O’reilly web page.
POSIX.4 Programmers Guide
Programming for the Real World
By Bill Gallmeister
First Edition September 1994
ISBN: 1-56592-074-0
570 pages, $39.95 US, $58.95 CA, £28.50 UK
POSIX Programmers Guide
By Donald Lewine
First Edition April 1991
ISBN: 0-937175-73-0
640 pages, $39.95 US, $59.95 CA, £28.50 UK