How can you tell who the author is for a Vatican document?

The referencing guide tells us that "conciliar documents - second Vatican council" should be referenced with Vatican Council II as the author. The question is, how do we know if the document is from the Vatican Council? A good way to know is to check the URL of the page.

In this case, we can see "ii vatican council" in the URL which tells us that it is a Vatican Council II document:

http://www.vatican.va/archive/hist_councils/ii_vatican_council/documents/vat-ii_const_19651207_gaudium-et-spes_en.html