If the document was issued after 1878, first consult the Papal archive on the Vatican Website. Note that many of the older materials may not be available in English.
If the document was issued after 1930 consult the Catholic Periodical Literature Index (in print) for 1930-2004 or the ATLA Religion Database for 1981-present. Within ATLA, go to Advanced Search and under genre, choose "papal document."
If the document was issued after 1740 and before 1978, check Papal Pronouncements: A Guide, 1740-1978.
For documents before 1740, consult the Papal Registers or the Librarian.
The Latin text represents the most authoritative version of a given document, with some exceptions; therefore, the Latin source is generally preferred for purposes of citation. In most of the above sources, only the Latin text is available. Certain significant Papal documents may be published in English as standalone publications. Other sources may contain English translations of Latin originals. These include the periodicals The Pope Speaks (1954-2005), L'Osservatore Romano [English Edition] (1968-present), and Origins (1971-present).
Another way to search the Maly Catalog is via subject headings:
Papal addresses and documents fall into certain recognized categories with levels of authority relative to each other. Below is a description of the major types of Papal documents, with those of greater solemnity near the top of the list. More details on some of these documents may be found in the New Catholic Encyclopedia.
The information for this guide was taken from Helen Hitchcock's article on the authority of church documents and Jimmy Akin's book Teaching with Authority: How to Cut Through Doctrinal Confusion & Understand What the Church Really Says.