books.google.com - The book claims that Yiddish was created when Judaized Sorbs first relexified their language to High German between the 9th-12th centuries; by the 15th century, the descendants of the Judaized Khazars also relexified their Kiev-Polessian (northern Ukrainian and southern Belarusian) speech to Yiddish...http://books.google.com/books/about/Two_Tiered_Relexification_in_Yiddish.html?id=JL7CY2MW63gC&utm_source=gb-gplus-shareTwo-Tiered Relexification in Yiddish
