Gaya APA
Riyanto, S.
(2015).
Easy IELTS: International English Language Testing System
.
Yogyakarta:
Pustaka Pelajar.
Gaya MLA
Riyanto, Slamet.
"Easy IELTS: International English Language Testing System".
Yogyakarta:
Pustaka Pelajar,
2015.
Text.