Does anyone know of any articles about gifted kids who are bored/frustrated but DO NOT act out?

I posted here a while ago, we are still having a few issues with DS4 and school. We are going to bat for differentiation next week, but i'm beginning to feel that Home school is our only option.

DS tells me that he doesn't want to go to school and he wants me to teach him "everything". He doesn't act up in class, does as he is told. But i see anxious behaviours and a sulleness that were not there in the school break. As he doesn't do this in class, the class teacher doesn't believe that he is different our side of school (obviously its hard to believe something that you don't see).

So anyway, i wanted a few articles to read. So i can see that there are other kids like my son who were bored/frustrated but behave well.
I did search online but everything was about acting out. Is there a secret stash of articles some where, or maybe some anecdotal stories?

Thanks, Mewzard.