APA
Arnold R. A., . (2012). Principles of economics 10th ed. [Place of publication not identified]: Cengage Learning.
Chicago
Arnold Roger A, . 2012. Principles of economics 10th ed. [Place of publication not identified]: Cengage Learning.
Harvard
Arnold R. A., . (2012). Principles of economics 10th ed. [Place of publication not identified]: Cengage Learning.
MLA
Arnold Roger A, . Principles of economics 10th ed. [Place of publication not identified]: Cengage Learning. 2012.