Don't know much about sheet music, but if you look under "countries" in Yahoo or some other search you'll find that some of the countries you're interested in will have lots of information (often not in English) on their traditional music, while others do not. It's worth a surf. I have to recommend a couple of my Central European favorites (never say Eastern Europe until you at least get as far as Ukraine). There is a wonderful Hungarian singer, Marta Sebestyen, and her band, Muszikas, that have about 10 albums available here, mostly on the Ryko/Hannibal labels. They are fine scholars as well as performers; you can learn a lot just from their liner notes. There is a Czech brother and sister team named Petr and Hana Ulrichovi, with their band Javory, who are also wonderful, but albums are harder to get here. If you like accordion, I'll highly recommend a Finnish player named Maria Kalamieni. I've gotten her albums from Amazon.com. Finally a Croatian band (with one album available on which they play mostly Bosnian music) called Vujisciscs. It's fascinating to listen to Middle Eastern music, go through Turkey, the Balkans, the Czechs, Poles, the Baltic countries on up into Scandinavia. You'll begin to hear an unbroken path of gradually changing styles of rythms, harmonies, and melodies. Good luck and have fun.

Chet W.