How do I remove and replace door mirror on 93 90CS

[EGOR46 at aol.com]

I have a broken door mirror on my 93 90CS.  Can I replace just the glass or 
does the entire assembly have to be replaced?  Seems logical that the glass 
should be replaceable by itself  but I don't see how it comes out.  I have a 
used replacement assembly which is still in a door, but after much searching 
I cannot see how it is attached.  Any advice will be appreciated.