any good books on dealing with aging parents?

[rgG]

This is a difficult conversation to have.
I don't know of any books, but I am sure there are many. We were lucky that my FIL volunteered to give up his keys, just before we were going to have to tell him he needed to.
The only thing I can say is to try and stress the positives of doing to on their own terms and not when they are incapacitated. Stress that this gives them plenty of time to get ready and plan, so it can go more slowly and hopefully smoothly.
Try to do it with love and understanding and hope for the best. We will all be there, eventually, and it isn't easy for either side.
At least they are already in a retirement community, so the move should be a little easier.