A positive externality of education is the benefit to all of society from an educated population. Negative externalities are unintended costs generated by the production of some goods and services
Not only Muslims speak of "people of the book"- this phrase is also known in Judaism (but in Judaism it only refers to the Jews).
From the point of view of Muslims, this phrase refers all the Abrahamic religions: it's Jews and Christians - the worshipers of God who don't acknowledge Muhammad.
They died probably, i mean the war was forever ago