There is a great deal of good literature out there.
I don't know if he would go thru a withdrawal, none of the people I have been in rehab with drank that small an amount. But given that he has done it for so long has to make you wonder about it. After a day of not drinking I wonder if his hands are shaky or if he is sweaty and nervous. Those were my first signs at the beginning of my journey. Also, from my experience and talking to other addicts, we are very seldom, if ever, honest with ourselves and others about the amount we are actually drinking. My poor hubby thought I was drinking 2 or 3 drinks a night. He was in a state of shock the day I went to him for help and confessed it was actually more than a fifth every day. So you can see I was in much worse shape than your hubby. Just remember that the person in real trouble is seldom, if ever, honest about it all. The shame is too great.