Gaya APA
Leo, S., Sudiyanto, O, H. (2007).
English for Academic Purpose Essay Writing (I -).
Yogyakarta:
Andi Offset.
Gaya MLA
Leo, Sutanto., Sudiyanto, Oktaviani, Hastu.
"English for Academic Purpose Essay Writing".
I -
Yogyakarta:
Andi Offset,
2007.
Text.