Below are some examples of how treaties and U.N. documents can be handled in Zotero. They are not intended to be the only way to handle these types of documents, but rather a starting point that can be adapted.
Citation in Zotero European Journal of International Law style:
Convention Relating to the Status of Refugees, 189 UNTS 137, 28 July 1951.
Citation in Zotero European Journal of International Law style:
Agreement Between France and Austria Concerning the Sojourn of Refugees Within the Meaning of the Convention Relating to the Status of Refugees (Geneva Convention of 28 July 1951 and Protocol Relating to the Status of Refugees of 31 January 1967), 985 UNTS 303, 21 October 1974.
Citation in Zotero European Journal of International Law style:
Declaration on the Granting of Independence to Colonial Countries and Peoples, Res 1514 (XV), U.N. GAOR, 14 December 1960.