Gaya APA
ETS, .
(2013).
Official TOEFL iBT® Tests with Audio, Volume 1
.
usa:
Mc Graw-Hill Book Company.
Gaya MLA
ETS, .
"Official TOEFL iBT® Tests with Audio, Volume 1".
usa:
Mc Graw-Hill Book Company,
2013.
Buku.