The book by Roy Strong Gloriana: The portraits of Queen Elizabeth is the leading work in this field and contains excellent information on most of her existing portraits, but unfortunately is out of print. His recently republished The Cult of Elizabeth is also useful.

Pomeroy, Elizabeth W. Reading the Portraits of Queen Elizabeth I  (1989)
 
 
 
 
 
 

If you can't find what you are  looking for, try searching on  the world wide web:     Web www.elizabethi.org