resources/info regarding anxiety? | ADHD Information

Perhaps it would help if you looked up one of the groups/websites for people who have "social anxiety"?  I've looked for books/ advice about children with anxiety problems but they are all either too generalized or address very severe anxiety.  My 8 yr. old daughter (no adhd) has significantly more social anxiety than what would be described as shyness but it's not to the extreme that most books on the subject deal with.  It is becoming a problem however, since she won't talk to her teacher except to answer a direct question but clams up if the answer requires more than a few words.  She won't ask questions if she doesn't understand an assignment or if she needs help- she wouldn't even tell the teacher (or nurse, principal or counselor) what happened when she fell off the monkey bars and gave herself a black eye; she just waited till the teacher noticed and sent her to the nurse for ice. 

I know a lot of you have kids with anxiety problems, and my adhd son has problems with it as well but with him we know what's causing it and how to help- with her I'm at a loss.  Can anyone point me in the direction of good books/info/helpful techniques?