Citing government documents can be confusing. Because government documents are usually not intended for commercial publication, they don't necessarily follow the well-established practices of commercial publishing houses. The information needed for a good citation may be confusingly presented, or may not be present at all. Also, government documents vary widely in purpose, style and content, and none of the standard style manuals gives examples for citing all of these materials in a consistent fashion.
Occasionally a government document will offer a suggested citation, usually on the front or back of the title page.