For books containing papers of the SDL Forum events see Proceedings.

UML 2 Illustrated - Developing Real-Time & Communications Systems
Laurent Doldi.
316 pages - Oct 2003 - ISBN 2-9516600-0-6
Companion to SDL Illustrated book by the same author.
The book can be ordered through your prefered book shop.
This book illustrates how MSC and SDL are now effectively embedded in UML!
Validation of Communications Systems with SDL: The Art of SDL Simulation and Reachability Analysis
Laurent Doldi.
310 pages - John Wiley & Sons - May 2003 - ISBN 0-470-85286-0
Companion to SDL Illustrated book by the same author.
SDL Illustrated - visually design executable models
Laurent Doldi. 270 pages - May 2001 - ISBN 2-9516600-0-6
Companion to Validation book by the same author.
The book should be ordered through your prefered book shop. Covers SDL-92 and SDL-2000.
Systems Engineering with SDL: Developing Performance-Critical Communication Systems
Andreas Mitschele-Thiel.
360 pages - John Wiley & Sons January 2001 - ISBN : 0-471-49875-0
SDL Modélisation de protocoles et systèmes réactifs (in French)
Zoubir  Mammeri .
624 pages - June 2000- ISBN : 2746201666
TIMe - The Integrated Method
The Integrated Method - a freely available integrated methodology based on UML, SDL and MSC.
Some of the authors are R. Bræk, J. Gorman, Ø. Haugen, G. Melby, B. Møller-Pedersen and R. Sanders
SDL - Formal Object-oriented Language for Communicating Systems.
Ellsberger, J.; Hogrefe, D.; Sarma, A.;
Prentice Hall Europe, 1997, ISBN 0-13-621384-7.
Nov 2003 - Out of Print--Limited Availability
Systems Engineering Using SDL-92  
A. Olsen, O. Færgemand, B. Møller-Pedersen, R. Reed and J. R. W. Smith.
Elsevier, 1994. ISBN 0-444-89872-7. Out of Print--Limited Availability
Engineering Real Time Systems
R. Bræk and Ø. Haugen. Prentice Hall 1993, ISBN 0-13-034448-6.
Information Processing systems, Open Systems Interconnection, Guidelines for the Application of Estelle, LOTOS and SDL
ITU, Geneva 1988. (same as ISO/IEC TR 10167 -:1991), and incorporated in
Turner (editor): Using Formal Description Techniques -- An Introduction to Estelle, LOTOS and SDL published by John Wiley & Sons, 1992).
Mar 2004 - Out of Print--Limited Availability but see the link
SDL With Applications From Protocol Specification
F. Belina, D. Hogrefe and A. Sarma. Prentice Hall 1991, ISBN 0-13-785890-6. Out of Print--Limited Availability
Telecommunications System Engineering Using SDL
Saracco, Smith and Reed. North-Holland 1989, ISBN 0 444 99084 4. This book is out of print, and the publisher has no intention to reprint, so the only way of obtaining a copy is from a library (it is available from the BCS/IEE Library,London) or from someone that has a copy. It does not cover SDL-92. Out of Print--Limited Availability
Ovum Evaluates: CASE Products
Ovum is an independent research company which publishes evaluations of (amongst other things) CASE tools and user friendly guides to CASE tool methods. They have evaluated the SDL method and the two main SDL tools (and many other real-time tools). The SDL method evaluation was available free download from the Ovum web site. The tool evaluations are described on the Web site and are available to subscribers to the CASE tool evaluation service.