Gaya APA

Azar, B, S., Hagen, S, A. (2009). UNDERSTANDING AND USING ENGLISH GRAMMAR + CD (4th). USA: PEARSON.

Gaya MLA

Azar, Betty, Schrampfer., Hagen, Stacy, A.. "UNDERSTANDING AND USING ENGLISH GRAMMAR + CD". 4th USA: PEARSON, 2009. Text.