Pratter’s guide provides a very useful framework for researching Travaux Préparatoires.
The travaux préparatoires (French: "preparatory works", in the plural) are the official record of a negotiation. Sometimes published, the "travaux" are often useful in clarifying the intentions of a treaty or other instrument. This is reflected in Article 32 of the Vienna Convention on the Law of Treaties (VCLT).
When interpreting treaties, the VCLT places this form of interpretation as secondary or less important than looking to the ordinary meaning (see Articles 31 and 32).
The travaux are often available to the public on the websites created for a specific treaty (such as the Rome Statute) or on the United Nations website.
Source: Wikipedia
United Nations Documentation: Research Guide
This guide is designed for researchers and information professionals with an interest in United Nations documentation. It presents an overview of the various types of documents and publications issued by the Organization (e.g, reports, resolutions, meeting records, sales publications, press releases) and gives guidance on how to work with them.
The Research Guide also provides information on actions taken by the General Assembly as well as the Security Council and introduces researchers to major fields of UN activities: environment, human rights, international law and peacekeeping.
United Nations Dipolmatic Conferences
This website provides access to the official records of a series of diplomatic conferences, convoked by the United Nations in order to negotiate and adopt several treaties based on drafts worked out by the International Law Commission and considered by the Sixth (Legal) Committee of the General Assembly.
The user is provided access by individual document, and the entire collection of proceedings is searchable in full-text format.