Dear Jackie: I searched for your "GuŞlac" using "th" instead of the "Ş", and found a whole long list of lovely sites about him and his sister Pega. I am indeed grateful to you for giving me a clue that will yield many pleasant hours of browsing.Just in case anyone else is interested, here is the URL:

http://www.umilta.net/pega.html

P.S. Interestingly, the manuscripts spell his name with "th" not with a "Ş".