First, check out the Golden Nuggets
section. There is a lot of good links there.
Second, he and his mother are NOT communicating. Each is going in circles, repeating the same thing over and over again without the other gaining anymore understanding than they did previously. This is not that uncommon, especially among family members. He needs to work on approaching the entire conversation differently. Don't get mad or offended when the other party gets confused or doesn't understand what you thought was perfectly clear, etc. They each will also have to be okay with "agreeing to disagree".