Periodicals are a very good source for information about the United Nations, its current developments, and its activities. Periodical articles are also a good place for locating citations to treaties and documents.
You can locate books about the UN and its activities by using the LRC/University Library Online Catalog. To find books by subject, do a Subject search using the phrase "united nations," and, if appropriate, more specific terms to indicate the particular body (e.g., Security Council, Human Rights Council) in which you are interested. To find publications from the UN, use the same approach, but use the Author field instead of Subject.
The Bluebook has special instructions for citing UN resolutions (see Rule 21.7.2), but it also permits, in the alternative, citing to an online version. The instructions below are useful only if you need to find a citation to the official records.
In addition to the resolution number, you need to find a page citation to the UN official records (e.g., for General Assembly resolutions, you need a citation to UN GAOR). To find this citation, you first need to find what UN document contains resolutions for the time period in which your resolution was passed. This UN document number is not the same as the number of the resolution.
To find the UN document containing your resolution, you can use either UNBisnet or UN-I-QUE. Search for the terms resolutions adopted by the general assembly in the title field. Specify the session in the title field also--e.g., 20th. You should get a list of documents with links to the full text in .pdf format. At the end of the document is an index to the resolutions and decisions contained in the document, giving the page number on which each one appears. Do NOT use the .pdf "find" function to look for your resolution, because the older .pdf documents are only images, with no functional text search.
If you need help, ask at the Reference Office.