Gaya APA
Azar, B, S. (1999).
Understanding And Using English Grammar Third Edition With Answer Key (Edisi 3).
New York:
Longman.
Gaya MLA
Azar, Betty, Schrampfer.
"Understanding And Using English Grammar Third Edition With Answer Key".
Edisi 3
New York:
Longman,
1999.
Text.