Recommendations for buying guide. Online or book

It has come time to give up my trusty MG midget. I'm looking for a
general primer in "Mustang". Something with a good general discription
of each year and model along with pictures. Not so much the early
classics, more the 1990's and up. I'm looking for a convertable to
cruse the local area.
The local dealers have only an occasional one. I will have to drive a
fair amount to look and don't want to inconvience someone selling a car
if I'm not really interested. Since I will probabley keep this car for
many years, I want to choose correctly.
Thanks in advance for any suggestions.