I'll leave it to all the experts to suggets a really good WAN book, But for just the CCNA stuff beleive it or not I found the CISCO CCNA Prep Library to be an excelent resource. The CCNA certification exam guide book covers all the WAN (pretty much just ISDN and F/R with a smatter of PPP) necessary for CCNA. I found it to be very close to the exam.
Another Fabulouse book for General networking (WAN included) is
Cisco certification - Bridges, Routers and Switches for CCIE's by Caslow
ISBN0-13-082537-9
That was pretty much all I used, actually I just passed today 913.
As a long time lurker thanks also to all the help AT forums has provided.
Thanks in particular to spidey07 - I have found his replies invaluable - btw I've been gone a while what were the results with the CCIE lab?
anyway tho just a pleeb i hope this helps
OM