The primary book of the Copenhagen School is Security: A New Framework for Analysis, authored by Buzan, Wæver and De Wilde.
In Security: A New Framework for Analysis, the authors list the following sectors: military/state, political, societal, economic, and environmental.
They contrast with the traditional idea of "buffer states" which are located at points where security dynamics are intense (e.g. Belgium between Germany and France).
Securitization, developed by Ole Wæver, is probably the most prominent concept of the Copenhagen School , and the one that has generated the most literature.
By making use of speech act a (state) actor tries to move a topic away from politics into an area of security concerns thereby legitimating extraordinary means against the socially constructed threat.
[2] Some of the most detailed books on the subject are: A criticism that has been advanced against the Copenhagen School is that it is a Eurocentric approach to security.