Gaya APA
Ekelund, R, B., Hebert, R, F. (1990).
A History of economic theory and method .
Singapore:
McGraw-Hill.
Gaya MLA
Ekelund, Robert, B.., Hebert, Robert, F..
"A History of economic theory and method".
Singapore:
McGraw-Hill,
1990.
Buku/Printed Material.