Prof. Manuel Ayau's "Not A Zero-Sum Game" is a brief but excellent summary of the concepts of comparative advantage and exchange and how this plays into trade. Ayau explains why trade is beneficial and debunks the arguments for government interference in the free market, emphasizing the idiotic anti-freedom "free trade" agreements.
The book can be purchased (in Spanish or English) from the bookstore of the Universidad Francisco Marroquín, which, by the way, is a bastion of Austro-libertarian thought.
