One of the major references in the USA for locating places in Germany is Kevan Hansen's series of German Map Guides published by FamilyRoots Publishing Company.
Koselitz (and Frauenhain, mentioned in this answer by lejonet) are included in Map Guide To German Parish Registers Vol 26 - Kingdom Of Saxony II.
Hansen's guides are finding aids to the parishes in the area, showing surrounding parishes and providing cross-references to FHL microfilms and contact information for local archives. The publisher's description says the series (which is still ongoing) is based on the place names as of 1870.
One of the WorldCat.org detail pages shows holdings for this volume in 19 libraries across the US and Canada, most notably the Allen County Public Library in Fort Wayne, Indiana, and the Toronto Public Library in Toronto, Ontario. (Some libraries have the entire series under one listing, so check the other entries for more libraries.)
Professional genealogists who do a lot of German research buy the whole series; for hobbyist genealogists, it's probably more practical to look up your parish at the library and decide afterwards whether you need to own the volumes for your towns of interest. If you can find a copy of this volume in a library near you, it can be valuable because the guide provides context for the entire area, such as information about the population centers and aids in determining reasonable distances of travel from one area to another.
(I am indebted to Dr. Michael D. Lacopo's lecture FR032 Finding and Utilizing German Church Records from the 2015 Jamboree, presented by the Southern California Genealogical Society, for the pointer to this valuable resource.)