Gaya APA

RUFFIN, R, J. (1988). PRINCIPLE OF ECONOMICS THIRD EDITION (3rd). Glenview,Illinois: Scott, Foresman And Company.

Gaya MLA

RUFFIN, Roy, J.. "PRINCIPLE OF ECONOMICS THIRD EDITION". 3rd Glenview,Illinois: Scott, Foresman And Company, 1988. Textbook.