Documentation
Between 1992 and 2000, the YIVO Institute for Jewish Research published a three-volume Language and Cultural Atlas of Ashkenazic Jewry, commonly referred to as the LCAAJ. This provides a detailed description of the phonetic elements of what is presented as an Eastern-Western dialect continuum, and mapping their geographic distribution. A more recent extensive phonetic description, also of both Eastern and Western Yiddish, is given by Neil G. Jacobs in Jacobs 2005.
Read more about this topic: Yiddish Dialects