The Bluebook offers detailed guidance for all sorts of U.S. materials, but it is less comprehensive for foreign jurisdictions. (Imagine how big it would be if it had the detail about other countries that it does for the U.S.!)
It gives guidance for citing materials from 43 selected foreign jurisdictions in T2, pp. 277-425.
The editors of two journals have prepared their own guides.
Guide to Foreign and International Legal Citations, by the New York University Journal of International Law and Politics, covers 45 countries. The first edition (2006) is available in PDF here. The second edition (2009) (which was commercially published) is available in print in the Reference Office (K89 .G84 2009).
The International Citation Manual (ICM), prepared by the editors of the Washington University Global Studies Law Review, covers 37 countries. Each has a several-page guide giving an overview its legal system and showing citation formats for different major publications (constitution, statutes, cases, etc.), with lots of examples.
There are many countries that appear in only one or two of the three manuals. The following chart summarizes the coverage.