Note different spellings of common words such as: labor/labour organization/organisation, cancellation/cancelation.
When using "Google", you can limit your search to the websites of organizations or governments by selecting "advanced search" and limiting the domain to ".org" or ".gov". See below for a sample search.
offers advice about judging quality of sources. It is written by the Reference Librarian for International and Foreign Law at New York University School of Law Library.
International Legal Research in a Global Community by 
International and Foreign Legal Research by 
International Legal Research in a Nutshell by 