D. Obal, Thaddeus J., A Bibliography for Genealogical Research Involving Polish Ancestry , 1978. Obal has self-published a few books on Polish genealogy, including lists of surnames, etc. The book listed is a good list of sources. Don't let the title fool you. This is a wonderful survey of Eastern European sources including church records.
Brief histories explain each region.
Please consult the excellent Jewish FAQ by Warren Blatt. Church Records 1. Roman Catholic 2. Jewish Please consult the excellent Jewish FAQ by Warren Blatt. Specifically, chapter 14.