Dover Publications has many great stained glass pattern design books,
Traditional, Art Deco, Victorian and even Tiffany designs.  They are for
sale on their site, very reasonably priced and are also available from
many art supply stores.  Dover also offers many of their publications as
E-Books and is a great source for many wonderful books.

Good luck and have fun with your project.

Rosemary West
Fallbrook, California