Consult Chris Davidson's LibGuide: List of Foreign Governments. This web site t provides links to the official websites of national governments.
For unrepresented nations, consult the UNPO (Unrepresented Nations and Peoples Organization.
To find contact information for a U.S. Embassy abroad, consult the U.S. Embassy web site.
Foreign embassies located in the United States can be found at the Department of State web site of foreign embassies.
Recommended SUBJECT search “business etiquette” [can insert region or country of choice]. Example: business etiquette asia