I've volunteered at the Wilmette Family History Center for a number of years and one of the perks in serving there is the chance to meet many talented and downright-pleasant-to-get-to-know researchers. Judith Frazin is one of them. She's the author of A Translation Guide to 19th-Century Polish-Language Civil-Registration Documents
(including Birth, Marriage and Death Records) and the newest edition of the book recently won her an achievement award from the International Association of Jewish Genealogical Societies.
If you are researching Polish ancestors, as many people who have Chicago roots are, take some time to explore this book!
Sample pages including table of contents
Check WorldCat to see if there's a copy available at a library near you. (The Wilmette FHC has one, if you're in the area.) If not, you can order it through the Jewish Genealogical Society of Illinois website.