1. Stolper, W.F., Samuelson, P.A.: Protection and real wages. Rev. Econ. Stud. 9(1), 58–73 (1941)
2. Hal, R.: Intermediate Microeconomics: A Modern Approach, p. 938. W.W. Norton, New York (1987)
3. Barthwal, R.: Industrial Economics: An Introductory Textbook. New Age International, New Delhi (2007)
4. Anderson, D.A.: Cracking the AP Economics Macro Micro Exams, vol. 9. Princeton Review, New York (2009)
5. Hall, R.E., Lieberman, M.: Macroeconomics: Principles and Applications, 6th edn. Longman, Harlow (1989)