Gaya APA

Principles of economics / Karl E. Case ; Ray C. Fair ; Sharon M. Oster. (2015). Harlow, Essex: Pearson Education, c.

Gaya MLA

Principles of economics / Karl E. Case ; Ray C. Fair ; Sharon M. Oster. 11th ed.. Harlow, Essex: Pearson Education, c, 2015. Buku Wajib.