I want to know the answer to the following question:
Whose 1980 book mentions "informal" economics?
All the background I'm provided with is that "The "informal" economics presented in Milton Friedman's massively influential popular work Free to Choose (1980), is explicitly Hayekian in its account of the price system as a system for transmitting and co-ordinating knowledge.". Is that enough to answer the question?
Answer: yes