You can get the address, phone number and a map through them also. Check the Art Glass World site for local studios, retailers, free patterns and more. Also check with your local arts education groups, art museums etc. Some of them offer classes or know who does. Ask your friends if they know of anyone in the area working in glass.
Word of mouth is an excellent resource.
Some studios are small and use that as their main advertising mode. There are many larger catalog retailers who have an Internet presence are well. Spend some time with your favorite search engine and you'll come up with many more. Many retailers of all sizes give out a free newsletter to their customers called Stained Glass News. You can't subscribe to it, so ask your retailer to contact them if they don't have it.