Using Justia Patent search combined with USPTO is a great tool. Here are a couple of links: http://patents.justia.com/search?q=GT+Advanced http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=1&f=G&l=50&co1=AND&d=PTXT&s1=%22GT+ADvanced%22&OS=