Gaya APA
Buku pintar IELTS (international English Language Testing System). (2017).
Yogyakarta:
B First.
Gaya Chicago
Buku pintar IELTS (international English Language Testing System).
.
Yogyakarta:
B First,
2017.
Text.
Gaya MLA
Buku pintar IELTS (international English Language Testing System).
.
Yogyakarta:
B First,
2017.
Text.
Gaya Turabian
Buku pintar IELTS (international English Language Testing System).
Yogyakarta:
B First,
2017.
Print.