How can I find information about the establishment of diplomatic relations between countries?

When states establish bilateral diplomatic relations, they may communicate this to other states in a variety of ways. 

If the states request the UN to communicate the information to the other UN Member States, a note verbale will be prepared with the following text:

"The enclosed communication, available in [language(s)], is transmitted to the permanent missions of the States Members of the United Nations at the request of the Permanent Representatives of [State A] and [State B] to the United Nations."

These materials have been collected by the Dag Hammarskjöld Library and catalogued. This collection begins in 1977; the documents are not available online. To search, use the keywords "diplomatic relations" and the name of a country.