Gaya APA
Hubbard, R, G., O'Brien, A, P.
(2013).
Economics
(
14th Ed.)
.
England:
Pearson Education International.
Gaya MLA
Hubbard, R, Glenn., O'Brien, Anthony, Patrick.
"Economics".
14th Ed.
England:
Pearson Education International,
2013.
Text.