Being a mom of three kids, my time to spend among the stacks in the library is particularly limited, so I rely on the power of the internet to do a lot of my legwork for me. One of my most favorite sites to use for research is the Rakow Research Library at the Corning Museum of Glass. Their Ask A Librarian feature is terrific for getting bibliography on a particular subject, and most of their materials are accessible through interlibrary loan. Actually, the entire Corning Museum is a wealth of research material. They publish a wide variety of books, journals and collection catalogs, too. Aaaand, you can go to the museum in Corning, NY and try out glassblowing, fusing, lampworking, and etching. I could spend days in Corning.
Another site that is fast becoming a favorite of mine is WorldCat, which makes it possible to search libraries all over the world. A great feature of this site is that once you enter your zipcode and click on any item in your search results list, you can find out which libraries closest to you have the item you are looking for. Of course, sometimes the closest library might be the University of Stockholm in Sweden! I think I will be using this site most often to make lists of materials to obtain through interlibrary loan, but also to discover what a couple of the less-obvious institutions in my hometown have to offer on the subject of ancient and medieval glass.
While I wouldn't recommend relying completely on the internet for your glass research, you will find a wealth of images and other interesting information available out there. Much of what you find doing internet searches will give you fantastic jumping-off points for further study. Enjoy!