International treaties
A treaty is an agreement under international law entered into by actors in international law, namely sovereign states and international organizations. A treaty may also be known as an (international) agreement, protocol, covenant, convention, pact, or exchange of letters, among other terms. Regardless of terminology, all of these forms of agreements are, under international law, equally considered treaties and the rules are the same.
Treaties can be loosely compared to contracts: both are means of willing parties assuming obligations among themselves, and a party to either that fails to live up to their obligations can be held liable under international law.
A treaty is an official, express written agreement that states use to legally bind themselves. A treaty is the official document which expresses that agreement in words; and it is also the objective outcome of a ceremonial occasion which acknowledges the parties and their defined relationships.
Source: Wikipedia
Selected bibliography
Agreements at the Global and Regional Levels
Vienna Convention on the Law of Treaties (1969) 
Regulatory and procedural guidelines and reference information
The World Bank Operational Manual OP 7.50 - Projects on International Waterways (2001)
The World Bank Bank Procedures BP 7.50 - Projects on International Waterways (2001)
The World Bank Operational Manual OP 4.37 - Safety of Dams (2001)
The World Bank Bank Procedures BP 4.37 - Safety of Dams (2001)
The World Bank Bank Procedures BP 4.37, Annex A - Dam Safety Reports: Content and Timing (2001)
The World Bank Operational Manual OP 4.01 - Environmental Assessment (1999)
The World Bank Operational Manual OP 4.01, Annex A - Definitions (1999)
The World Bank Operational Manual OP 4.01, Annex C - Environmental Management Plan (1999)
The World Bank Bank Procedures BP 4.01 - Environmental Assessment (1999)
The World Bank Operational Manual OP 4.04 - Natural Habitats (2001)
The World Bank Operational Manual OP 4.04, Annex A - Definitions (2001)
The World Bank Bank Procedures BP 4.04 - Natural Habitats (2001)
Resources
