Take the picture to a local retailer that specializes in wallpaper and I am sure they'll be able to help you. They even keep old sample books (like sewing pattern books) that you can go through to find all the info you need.
Have you tried wallpaperwholeseller.com? Their selection of new and discontinued wallpapers is vast. They have helped me on several occassions and their prices are very reasonaable.
Login using the form on the top of the page to post feedback (if you are a registered user). If you have not yet registered, click here to do so. It's FREE!.