You have this backwards
(A cross between (I think) Silkie and Australian terrior. Originally bred at about 18 lbs) The Yorkie and the Australian Terrier were bred to create the Silky Terrier. I do have a lot about the history of the yorkies on my site, and I am always looking for more information to add. You can read about the history here.
http://yorkieviews.com/yorkiehistory.htm