On the schools of thought definition, I have used this one: a group
of scholars who hark back to a single writer or small number of writers for
inspiration and/or doctrinal support. Hence the modern Austrian school (in the
US) harks back to Carl Menger. There are other Austrian schools (in
Germany for example) that hark back to Boehm-Bawerk. The classical school (so named by
Marx) but typically hark back to Adam Smith, etc. Marxists hark back to what's his name.
I hope this helps.
Laurence S. Moss