@book{Varian_2014a, address={New York}, edition={Ninth edition}, title={Intermediate microeconomics: a modern approach}, publisher={W.W. Norton & Company}, author={Varian, Hal R.}, year={2014} }
@book{Varian_2014b, address={New York}, edition={First edition}, title={Intermediate microeconomics with calculus}, publisher={W.W. Norton & Company}, author={Varian, Hal R.}, year={2014} }