Book reccomendation please for parents with Autistic/Aspergers adult Son

Hi Everyone

I am still learning how this group works, and I am not used to discussing this with anyone, so not sure on alot of terminology etc, so please bare with me.

My son is late 20's, has undiagnosed Autism and/or aspergers, he has a successful career mainly working from home.  He has no interest in socialising and is extremely driven, is sensitive to noise, hates any change and has a very disciplined daily routine. I can see clearly, that he suffers terribly with anxiety, this is something I can understand.

Can anyone recommend a book that can help me understand him more as he will not communicate with me, and I want to learn how I can reach him, my previous post explains more.

Many thanks x